Bump start plugin to 0.15.0 (#1956)

Most important change is a fix for processes CPU usage calculation (see https://github.com/heim-rs/heim/issues/246)

.azure/azure-pipelines.yml

@@ -46,13 +46,13 @@ steps:
       echo "##vso[task.prependpath]$HOME/.cargo/bin"
       rustup component add rustfmt
     displayName: Install Rust
-  - bash: RUSTFLAGS="-D warnings" cargo test --all --features stable,test-bins
+  - bash: RUSTFLAGS="-D warnings" cargo test --all --features stable
     condition: eq(variables['style'], 'unflagged')
     displayName: Run tests
   - bash: RUSTFLAGS="-D warnings" cargo clippy --all --features=stable -- -D clippy::result_unwrap_used -D clippy::option_unwrap_used
     condition: eq(variables['style'], 'unflagged')
     displayName: Check clippy lints
-  - bash: NUSHELL_ENABLE_ALL_FLAGS=1 RUSTFLAGS="-D warnings" cargo test --all --features stable,test-bins
+  - bash: NUSHELL_ENABLE_ALL_FLAGS=1 RUSTFLAGS="-D warnings" cargo test --all --features stable
     condition: eq(variables['style'], 'canary')
     displayName: Run tests
   - bash: NUSHELL_ENABLE_ALL_FLAGS=1 RUSTFLAGS="-D warnings" cargo clippy --all --features=stable -- -D clippy::result_unwrap_used -D clippy::option_unwrap_used

.github/ISSUE_TEMPLATE/bug_report.md

@@ -23,8 +23,8 @@ A clear and concise description of what you expected to happen.
 If applicable, add screenshots to help explain your problem.
 
 **Configuration (please complete the following information):**
- - OS: [e.g. Windows]
+ - OS (e.g. Windows):
- - Version [e.g. 0.4.0]
+ - Nu version (you can use the `version` command to find out): 
- - Optional features (if any)
+ - Optional features (if any):
 
 Add any other context about the problem here.

.github/workflows/docker-publish.yml

@@ -13,7 +13,7 @@ jobs:
         - x86_64-unknown-linux-musl
         - x86_64-unknown-linux-gnu
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2
     - name: Install rust-embedded/cross
       env: { VERSION: v0.1.16 }
       run: >-
@@ -62,7 +62,7 @@ jobs:
         - { tag: glibc,            base-image: scratch,                    arch: x86_64-unknown-linux-gnu,  plugin: false, use-patch: false}
         - { tag: musl,             base-image: scratch,                    arch: x86_64-unknown-linux-musl, plugin: false, use-patch: false}
     steps:
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2
     - uses: actions/download-artifact@master
       with: { name: '${{ matrix.arch }}', path: target/release }
     - name: Build and publish exact version

CODE_OF_CONDUCT.md

@@ -55,7 +55,7 @@ a project may be further defined and clarified by project maintainers.
 ## Enforcement
 
 Instances of abusive, harassing, or otherwise unacceptable behavior may be
-reported by contacting the project team at wycats@gmail.com. All
+reported by contacting the project team at wycats@gmail.com via email or by reaching out to @jturner, @gedge, or @andras_io on discord. All
 complaints will be reviewed and investigated and will result in a response that
 is deemed necessary and appropriate to the circumstances. The project team is
 obligated to maintain confidentiality with regard to the reporter of an incident.

CONTRIBUTING.md

@@ -19,10 +19,40 @@ cd nushell
 cargo build
 ```
 
-## Tests
+## Useful Commands
 
-Run tests with:
+Build and run Nushell:
 
 ```shell
-cargo test --all --features=stable,test-bins
+cargo build --release && cargo run --release
+```
+
+Run Clippy on Nushell:
+
+```shell
+cargo clippy --all --features=stable
+```
+
+Run all tests:
+
+```shell
+cargo test --all --features=stable
+```
+
+Run all tests for a specific command
+
+```shell
+cargo test --package nu-cli --test main -- commands::<command_name_here>
+```
+
+Check to see if there are code formatting issues
+
+```shell
+cargo fmt --all -- --check
+```
+
+Format the code in the project
+
+```shell
+cargo fmt --all
 ```

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "nu"
-version = "0.14.0"
+version = "0.15.0"
 authors = ["The Nu Project Contributors"]
 description = "A new type of shell"
 license = "MIT"
@@ -18,32 +18,30 @@ members = ["crates/*/"]
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-nu-cli = { version = "0.14.0", path = "./crates/nu-cli" }
+nu-cli = { version = "0.15.0", path = "./crates/nu-cli" }
-nu-source = { version = "0.14.0", path = "./crates/nu-source" }
+nu-source = { version = "0.15.0", path = "./crates/nu-source" }
-nu-plugin = { version = "0.14.0", path = "./crates/nu-plugin" }
+nu-plugin = { version = "0.15.0", path = "./crates/nu-plugin" }
-nu-protocol = { version = "0.14.0", path = "./crates/nu-protocol" }
+nu-protocol = { version = "0.15.0", path = "./crates/nu-protocol" }
-nu-errors = { version = "0.14.0", path = "./crates/nu-errors" }
+nu-errors = { version = "0.15.0", path = "./crates/nu-errors" }
-nu-parser = { version = "0.14.0", path = "./crates/nu-parser" }
+nu-parser = { version = "0.15.0", path = "./crates/nu-parser" }
-nu-value-ext = { version = "0.14.0", path = "./crates/nu-value-ext" }
+nu-value-ext = { version = "0.15.0", path = "./crates/nu-value-ext" }
-nu_plugin_average = { version = "0.14.0", path = "./crates/nu_plugin_average", optional=true }
+nu_plugin_binaryview = { version = "0.15.0", path = "./crates/nu_plugin_binaryview", optional=true }
-nu_plugin_binaryview = { version = "0.14.0", path = "./crates/nu_plugin_binaryview", optional=true }
+nu_plugin_fetch = { version = "0.15.0", path = "./crates/nu_plugin_fetch", optional=true }
-nu_plugin_fetch = { version = "0.14.0", path = "./crates/nu_plugin_fetch", optional=true }
+nu_plugin_inc = { version = "0.15.0", path = "./crates/nu_plugin_inc", optional=true }
-nu_plugin_inc = { version = "0.14.0", path = "./crates/nu_plugin_inc", optional=true }
+nu_plugin_match = { version = "0.15.0", path = "./crates/nu_plugin_match", optional=true }
-nu_plugin_match = { version = "0.14.0", path = "./crates/nu_plugin_match", optional=true }
+nu_plugin_post = { version = "0.15.0", path = "./crates/nu_plugin_post", optional=true }
-nu_plugin_post = { version = "0.14.0", path = "./crates/nu_plugin_post", optional=true }
+nu_plugin_ps = { version = "0.15.0", path = "./crates/nu_plugin_ps", optional=true }
-nu_plugin_ps = { version = "0.14.0", path = "./crates/nu_plugin_ps", optional=true }
+nu_plugin_start = { version = "0.15.0", path = "./crates/nu_plugin_start", optional=true }
-nu_plugin_start = { version = "0.1.0", path = "./crates/nu_plugin_start", optional=true }
+nu_plugin_sys = { version = "0.15.0", path = "./crates/nu_plugin_sys", optional=true }
-nu_plugin_str = { version = "0.14.0", path = "./crates/nu_plugin_str", optional=true }
+nu_plugin_textview = { version = "0.15.0", path = "./crates/nu_plugin_textview", optional=true }
-nu_plugin_sys = { version = "0.14.0", path = "./crates/nu_plugin_sys", optional=true }
+nu_plugin_tree = { version = "0.15.0", path = "./crates/nu_plugin_tree", optional=true }
-nu_plugin_textview = { version = "0.14.0", path = "./crates/nu_plugin_textview", optional=true }
-nu_plugin_tree = { version = "0.14.0", path = "./crates/nu_plugin_tree", optional=true }
 
-crossterm = { version = "0.17.2", optional = true }
+crossterm = { version = "0.17.5", optional = true }
-semver = { version = "0.9.0", optional = true }
+semver = { version = "0.10.0", optional = true }
-syntect = { version = "4.1", default-features = false, features = ["default-fancy"], optional = true}
+syntect = { version = "4.2", default-features = false, features = ["default-fancy"], optional = true}
 url = { version = "2.1.1", optional = true }
 
-clap = "2.33.0"
+clap = "2.33.1"
 ctrlc = "3.1.4"
 dunce = "1.0.0"
 futures = { version = "0.3", features = ["compat", "io-compat"] }
@@ -51,29 +49,24 @@ log = "0.4.8"
 pretty_env_logger = "0.4.0"
 
 [dev-dependencies]
-nu-test-support = { version = "0.14.0", path = "./crates/nu-test-support" }
+nu-test-support = { version = "0.15.0", path = "./crates/nu-test-support" }
 
 [build-dependencies]
 toml = "0.5.6"
-serde = { version = "1.0.106", features = ["derive"] }
+serde = { version = "1.0.110", features = ["derive"] }
-nu-build = { version = "0.14.0", path = "./crates/nu-build" }
+nu-build = { version = "0.15.0", path = "./crates/nu-build" }
 
 [features]
-# Test executables
+default = ["sys", "ps", "textview", "inc"]
-test-bins = []
+stable = ["default", "starship-prompt", "binaryview", "match", "tree", "post", "fetch", "clipboard-cli", "trash-support", "start"]
-
-default = ["sys", "ps", "textview", "inc", "str"]
-stable = ["default", "starship-prompt", "binaryview", "match", "tree", "average", "post", "fetch", "clipboard-cli", "trash-support", "start"]
 
 # Default
 textview = ["crossterm", "syntect", "url", "nu_plugin_textview"]
 sys = ["nu_plugin_sys"]
 ps = ["nu_plugin_ps"]
 inc = ["semver", "nu_plugin_inc"]
-str = ["nu_plugin_str"]
 
 # Stable
-average = ["nu_plugin_average"]
 binaryview = ["nu_plugin_binaryview"]
 fetch = ["nu_plugin_fetch"]
 match = ["nu_plugin_match"]
@@ -86,31 +79,6 @@ clipboard-cli = ["nu-cli/clipboard-cli"]
 starship-prompt = ["nu-cli/starship-prompt"]
 trash-support = ["nu-cli/trash-support"]
 
-[[bin]]
-name = "fail"
-path = "crates/nu-test-support/src/bins/fail.rs"
-required-features = ["test-bins"]
-
-[[bin]]
-name = "chop"
-path = "crates/nu-test-support/src/bins/chop.rs"
-required-features = ["test-bins"]
-
-[[bin]]
-name = "cococo"
-path = "crates/nu-test-support/src/bins/cococo.rs"
-required-features = ["test-bins"]
-
-[[bin]]
-name = "nonu"
-path = "crates/nu-test-support/src/bins/nonu.rs"
-required-features = ["test-bins"]
-
-[[bin]]
-name = "iecho"
-path = "crates/nu-test-support/src/bins/iecho.rs"
-required-features = ["test-bins"]
-
 # Core plugins that ship with `cargo install nu` by default
 # Currently, Cargo limits us to installing only one binary
 # unless we use [[bin]], so we use this as a workaround
@@ -129,22 +97,12 @@ name = "nu_plugin_core_ps"
 path = "src/plugins/nu_plugin_core_ps.rs"
 required-features = ["ps"]
 
-[[bin]]
-name = "nu_plugin_core_str"
-path = "src/plugins/nu_plugin_core_str.rs"
-required-features = ["str"]
-
 [[bin]]
 name = "nu_plugin_core_sys"
 path = "src/plugins/nu_plugin_core_sys.rs"
 required-features = ["sys"]
 
 # Stable plugins
-[[bin]]
-name = "nu_plugin_stable_average"
-path = "src/plugins/nu_plugin_stable_average.rs"
-required-features = ["average"]
-
 [[bin]]
 name = "nu_plugin_stable_fetch"
 path = "src/plugins/nu_plugin_stable_fetch.rs"

README.md

@@ -44,7 +44,7 @@ Try it in Gitpod.
 
 Up-to-date installation instructions can be found in the [installation chapter of the book](https://www.nushell.sh/book/en/installation.html).  **Windows users**: please note that Nu works on Windows 10 and does not currently have Windows 7/8.1 support.
 
-To build Nu, you will need to use the **latest stable (1.39 or later)** version of the compiler.
+To build Nu, you will need to use the **latest stable (1.41 or later)** version of the compiler.
 
 Required dependencies:
 
@@ -144,19 +144,20 @@ Commands that work in the pipeline fit into one of three categories:
 Commands are separated by the pipe symbol (`|`) to denote a pipeline flowing left to right.
 
 ```
-/home/jonathan/Source/nushell(master)> ls | where type == "Directory" | autoview
+/home/jonathan/Source/nushell(master)> ls | where type == "Dir" | autoview
-────┬───────────┬───────────┬──────────┬────────┬──────────────┬────────────────
+───┬────────┬──────┬────────┬──────────────
- #  │ name      │ type      │ readonly │ size   │ accessed     │ modified
+ # │ name   │ type │ size   │ modified
-────┼───────────┼───────────┼──────────┼────────┼──────────────┼────────────────
+───┼────────┼──────┼────────┼──────────────
-  0 │ .azure    │ Directory │          │ 4.1 KB │ 2 months ago │ a day ago
+ 0 │ assets │ Dir  │ 4.1 KB │ 1 week ago
-  1 │ target    │ Directory │          │ 4.1 KB │ 3 days ago   │ 3 days ago
+ 1 │ crates │ Dir  │ 4.1 KB │ 4 days ago
-  2 │ images    │ Directory │          │ 4.1 KB │ 2 months ago │ 2 weeks ago
+ 2 │ debian │ Dir  │ 4.1 KB │ 1 week ago
-  3 │ tests     │ Directory │          │ 4.1 KB │ 2 months ago │ 37 minutes ago
+ 3 │ docker │ Dir  │ 4.1 KB │ 1 week ago
-  4 │ tmp       │ Directory │          │ 4.1 KB │ 2 weeks ago  │ 2 weeks ago
+ 4 │ docs   │ Dir  │ 4.1 KB │ 1 week ago
-  5 │ src       │ Directory │          │ 4.1 KB │ 2 months ago │ 37 minutes ago
+ 5 │ images │ Dir  │ 4.1 KB │ 1 week ago
-  6 │ assets    │ Directory │          │ 4.1 KB │ a month ago  │ a month ago
+ 6 │ src    │ Dir  │ 4.1 KB │ 1 week ago
-  7 │ docs      │ Directory │          │ 4.1 KB │ 2 months ago │ 2 months ago
+ 7 │ target │ Dir  │ 4.1 KB │ 23 hours ago
-────┴───────────┴───────────┴──────────┴────────┴──────────────┴────────────────
+ 8 │ tests  │ Dir  │ 4.1 KB │ 1 week ago
+───┴────────┴──────┴────────┴──────────────
 ```
 
 Because most of the time you'll want to see the output of a pipeline, `autoview` is assumed.
@@ -171,14 +172,15 @@ For example, we could use the built-in `ps` command as well to get a list of the
 
 ```text
 /home/jonathan/Source/nushell(master)> ps | where cpu > 0
-───┬───────┬─────────────────┬──────────┬──────────
+───┬────────┬───────────────────┬──────────┬─────────┬──────────┬──────────
- # │ pid   │ name            │ status   │ cpu
+ # │ pid    │ name              │ status   │ cpu     │ mem      │ virtual
-───┼───────┼─────────────────┼──────────┼──────────
+───┼────────┼───────────────────┼──────────┼─────────┼──────────┼──────────
- 0 │   992 │ chrome          │ Sleeping │ 6.988768
+ 0 │    435 │ irq/142-SYNA327   │ Sleeping │  7.5699 │      0 B │      0 B
- 1 │  4240 │ chrome          │ Sleeping │ 5.645982
+ 1 │   1609 │ pulseaudio        │ Sleeping │  6.5605 │  10.6 MB │   2.3 GB
- 2 │ 13973 │ qemu-system-x86 │ Sleeping │ 4.996551
+ 2 │   1625 │ gnome-shell       │ Sleeping │  6.5684 │ 639.6 MB │   7.3 GB
- 3 │ 15746 │ nu              │ Sleeping │ 84.59905
+ 3 │   2202 │ Web Content       │ Sleeping │  6.8157 │ 320.8 MB │   3.0 GB
-───┴───────┴─────────────────┴──────────┴──────────
+ 4 │ 328788 │ nu_plugin_core_ps │ Sleeping │ 92.5750 │   5.9 MB │ 633.2 MB
+───┴────────┴───────────────────┴──────────┴─────────┴──────────┴──────────
 ```
 
 ## Opening files
@@ -188,45 +190,49 @@ For example, you can load a .toml file as structured data and explore it:
 
 ```
 /home/jonathan/Source/nushell(master)> open Cargo.toml
-──────────────────┬────────────────┬──────────────────
+────────────────────┬───────────────────────────
- bin              │ dependencies   │ dev-dependencies
+ bin                │ [table 18 rows]
-──────────────────┼────────────────┼──────────────────
+ build-dependencies │ [row nu-build serde toml]
- [table: 12 rows] │ [table: 1 row] │ [table: 1 row]
+ dependencies       │ [row 29 columns]
-──────────────────┴────────────────┴──────────────────
+ dev-dependencies   │ [row nu-test-support]
+ features           │ [row 19 columns]
+ package            │ [row 12 columns]
+ workspace          │ [row members]
+────────────────────┴───────────────────────────
 ```
 
 We can pipeline this into a command that gets the contents of one of the columns:
 
 ```
 /home/jonathan/Source/nushell(master)> open Cargo.toml | get package
-─────────────────┬────────────────────────────┬─────────┬─────────┬──────┬─────────
+───────────────┬────────────────────────────────────
- authors         │ description                │ edition │ license │ name │ version
+ authors       │ [table 1 rows]
-─────────────────┼────────────────────────────┼─────────┼─────────┼──────┼─────────
+ default-run   │ nu
- [table: 3 rows] │ A shell for the GitHub era │ 2018    │ MIT     │ nu   │ 0.9.0
+ description   │ A new type of shell
-─────────────────┴────────────────────────────┴─────────┴─────────┴──────┴─────────
+ documentation │ https://www.nushell.sh/book/
+ edition       │ 2018
+ exclude       │ [table 1 rows]
+ homepage      │ https://www.nushell.sh
+ license       │ MIT
+ name          │ nu
+ readme        │ README.md
+ repository    │ https://github.com/nushell/nushell
+ version       │ 0.14.1
+───────────────┴────────────────────────────────────
 ```
 
 Finally, we can use commands outside of Nu once we have the data we want:
 
 ```
 /home/jonathan/Source/nushell(master)> open Cargo.toml | get package.version | echo $it
-0.9.0
+0.14.1
 ```
 
 Here we use the variable `$it` to refer to the value being piped to the external command.
 
 ## Configuration
 
-Nu has early support for configuring the shell. It currently supports the following settings:
+Nu has early support for configuring the shell. You can refer to the book for a list of [all supported variables](https://www.nushell.sh/book/en/configuration.html).
-
-| Variable        | Type                 | Description                                                    |
-| --------------- | -------------------- | -------------------------------------------------------------- |
-| path            | table of strings     | PATH to use to find binaries                                   |
-| env             | row                  | the environment variables to pass to external commands         |
-| ctrlc_exit      | boolean              | whether or not to exit Nu after multiple ctrl-c presses        |
-| table_mode      | "light" or other     | enable lightweight or normal tables                            |
-| edit_mode       | "vi" or "emacs"      | changes line editing to "vi" or "emacs" mode                   |
-| completion_mode | "circular" or "list" | changes completion type to "circular" (default) or "list" mode |
 
 To set one of these variables, you can use `config --set`. For example:
 
@@ -276,6 +282,27 @@ Nu adheres closely to a set of goals that make up its design philosophy. As feat
 
 You can find a list of Nu commands, complete with documentation, in [quick command references](https://www.nushell.sh/documentation.html#quick-command-references).
 
+# Progress
+
+Nu is in heavy development, and will naturally change as it matures and people use it.  The chart below isn't meant to be exhaustive, but rather helps give an idea for some of the areas of development and their relative completion:
+
+| Features | Not started | Prototype | MVP | Preview | Mature | Notes
+| -------- |:-----------:|:---------:|:---:|:-------:|:------:| -----
+| Aliases  |             |     X     |     |         |        | Initial implementation but lacks necessary features
+| Notebook |             |     X     |     |         |        | Initial jupyter support, but it loses state and lacks features
+| File ops |             |           |  X  |         |        | cp, mv, rm, mkdir have some support, but lacking others 
+| Environment |          |     X     |     |         |        | Temporary environment, but no session-wide env variables 
+| Shells   |             |     X     |     |         |        | Basic value and file shells, but no opt-in/opt-out for commands
+| Protocol |             |           |  X  |         |        | Streaming protocol is serviceable
+| Plugins  |             |     X     |     |         |        | Plugins work on one row at a time, lack batching and expression eval 
+| Errors   |             |           |  X  |         |        | Error reporting works, but could use usability polish
+| Documentation |        |     X     |     |         |        | Book and related are barebones and lack task-based lessons
+| Paging   |             |     X     |     |         |        | Textview has paging, but we'd like paging for tables
+| Functions|      X      |           |     |         |        | No functions, yet, only aliases
+| Variables|      X      |           |     |         |        | Nu doesn't yet support variables 
+| Completions |          |     X     |     |         |        | Completions are currently barebones, at best
+| Type-checking |        |     X     |     |         |        | Commands check basic types, but input/output isn't checked
+
 # Contributing
 
 See [Contributing](CONTRIBUTING.md) for details.

crates/nu-build/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "nu-build"
-version = "0.14.0"
+version = "0.15.0"
 authors = ["The Nu Project Contributors"]
 edition = "2018"
 description = "Core build system for nushell"
@@ -10,7 +10,7 @@ license = "MIT"
 doctest = false
 
 [dependencies]
-serde = { version = "1.0.106", features = ["derive"] }
+serde = { version = "1.0.110", features = ["derive"] }
 lazy_static = "1.4.0"
-serde_json = "1.0.51"
+serde_json = "1.0.53"
 toml = "0.5.6"

crates/nu-cli/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "nu-cli"
-version = "0.14.0"
+version = "0.15.0"
 authors = ["The Nu Project Contributors"]
 description = "CLI for nushell"
 edition = "2018"
@@ -10,27 +10,29 @@ license = "MIT"
 doctest = false
 
 [dependencies]
-nu-source = { version = "0.14.0", path = "../nu-source" }
+nu-source = { version = "0.15.0", path = "../nu-source" }
-nu-plugin = { version = "0.14.0", path = "../nu-plugin" }
+nu-plugin = { version = "0.15.0", path = "../nu-plugin" }
-nu-protocol = { version = "0.14.0", path = "../nu-protocol" }
+nu-protocol = { version = "0.15.0", path = "../nu-protocol" }
-nu-errors = { version = "0.14.0", path = "../nu-errors" }
+nu-errors = { version = "0.15.0", path = "../nu-errors" }
-nu-parser = { version = "0.14.0", path = "../nu-parser" }
+nu-parser = { version = "0.15.0", path = "../nu-parser" }
-nu-value-ext = { version = "0.14.0", path = "../nu-value-ext" }
+nu-value-ext = { version = "0.15.0", path = "../nu-value-ext" }
-nu-test-support = { version = "0.14.0", path = "../nu-test-support" }
+nu-test-support = { version = "0.15.0", path = "../nu-test-support" }
-
 
 ansi_term = "0.12.1"
 app_dirs = "1.2.1"
+async-recursion = "0.3.1"
+async-trait = "0.1.31"
+directories = "2.0.2"
 async-stream = "0.2"
-base64 = "0.12.0"
+base64 = "0.12.1"
-bigdecimal = { version = "0.1.0", features = ["serde"] }
+bigdecimal = { version = "0.1.2", features = ["serde"] }
 bson = { version = "0.14.1", features = ["decimal128"] }
-byte-unit = "3.0.3"
+byte-unit = "3.1.3"
 bytes = "0.5.4"
 calamine = "0.16"
 cfg-if = "0.1"
 chrono = { version = "0.4.11", features = ["serde"] }
-clap = "2.33.0"
+clap = "2.33.1"
 csv = "1.1"
 ctrlc = "3.1.4"
 derive-new = "0.5.8"
@@ -39,10 +41,10 @@ dunce = "1.0.0"
 eml-parser = "0.1.0"
 filesize = "0.2.0"
 futures = { version = "0.3", features = ["compat", "io-compat"] }
-futures-util = "0.3.4"
+futures-util = "0.3.5"
 futures_codec = "0.4"
-getset = "0.1.0"
+getset = "0.1.1"
-git2 = { version = "0.13.1", default_features = false }
+git2 = { version = "0.13.6", default_features = false }
 glob = "0.3.0"
 hex = "0.4"
 htmlescape = "0.3.1"
@@ -50,14 +52,14 @@ ical = "0.6.*"
 ichwh = "0.3.4"
 indexmap = { version = "1.3.2", features = ["serde-1"] }
 itertools = "0.9.0"
-language-reporting = "0.4.0"
+codespan-reporting = "0.9.4"
 log = "0.4.8"
 meval = "0.2"
 natural = "0.5.0"
 num-bigint = { version = "0.2.6", features = ["serde"] }
 num-traits = "0.2.11"
-parking_lot = "0.10.0"
+parking_lot = "0.10.2"
-pin-utils = "0.1.0-alpha.4"
+pin-utils = "0.1.0"
 pretty-hex = "0.1.1"
 pretty_env_logger = "0.4.0"
 prettytable-rs = "0.8.0"
@@ -65,13 +67,13 @@ ptree = {version = "0.2" }
 query_interface = "0.3.5"
 rand = "0.7"
 regex = "1"
-roxmltree = "0.10.1"
+roxmltree = "0.11.0"
-rustyline = "6.1.2"
+rustyline = "6.2.0"
-serde = { version = "1.0.106", features = ["derive"] }
+serde = { version = "1.0.110", features = ["derive"] }
 serde-hjson = "0.9.1"
-serde_bytes = "0.11.3"
+serde_bytes = "0.11.4"
 serde_ini = "0.2.0"
-serde_json = "1.0.51"
+serde_json = "1.0.53"
 serde_urlencoded = "0.6.1"
 serde_yaml = "0.8"
 shellexpand = "2.0.0"
@@ -82,24 +84,24 @@ termcolor = "1.1.0"
 textwrap = {version = "0.11.0", features = ["term_size"]}
 toml = "0.5.6"
 typetag = "0.1.4"
-umask = "0.1"
+umask = "1.0.0"
 unicode-xid = "0.2.0"
 which = "3"
 
-trash = { version = "1.0.0", optional = true }
+trash = { version = "1.0.1", optional = true }
 clipboard = { version = "0.5", optional = true }
-starship = { version = "0.39.0", optional = true }
+starship = { version = "0.41.3", optional = true }
 rayon = "1.3.0"
 
 [target.'cfg(unix)'.dependencies]
 users = "0.10.0"
 
 [dependencies.rusqlite]
-version = "0.22.0"
+version = "0.23.1"
 features = ["bundled", "blob"]
 
 [build-dependencies]
-nu-build = { version = "0.14.0", path = "../nu-build" }
+nu-build = { version = "0.15.0", path = "../nu-build" }
 
 [dev-dependencies]
 quickcheck = "0.9"

crates/nu-cli/src/cli.rs

@@ -8,11 +8,12 @@ use crate::context::Context;
 use crate::git::current_branch;
 use crate::path::canonicalize;
 use crate::prelude::*;
+use crate::EnvironmentSyncer;
 use futures_codec::FramedRead;
 
 use nu_errors::ShellError;
 use nu_protocol::hir::{ClassifiedCommand, Expression, InternalCommand, Literal, NamedArguments};
-use nu_protocol::{Primitive, ReturnSuccess, Scope, Signature, UntaggedValue, Value};
+use nu_protocol::{Primitive, ReturnSuccess, Signature, UntaggedValue, Value};
 
 use log::{debug, trace};
 use rustyline::error::ReadlineError;
@@ -109,13 +110,19 @@ fn search_paths() -> Vec<std::path::PathBuf> {
         }
     }
 
-    #[cfg(not(debug_assertions))]
+    if let Ok(config) = crate::data::config::config(Tag::unknown()) {
-    {
+        if let Some(plugin_dirs) = config.get("plugin_dirs") {
-        match env::var_os("PATH") {
+            if let Value {
-            Some(paths) => {
+                value: UntaggedValue::Table(pipelines),
-                search_paths.extend(env::split_paths(&paths).collect::<Vec<_>>());
+                ..
+            } = plugin_dirs
+            {
+                for pipeline in pipelines {
+                    if let Ok(plugin_dir) = pipeline.as_string() {
+                        search_paths.push(PathBuf::from(plugin_dir));
+                    }
+                }
             }
-            None => println!("PATH is not defined in the environment."),
         }
     }
 
@@ -278,12 +285,25 @@ pub fn create_default_context(
             whole_stream_command(Autoview),
             whole_stream_command(Table),
             // Text manipulation
+            whole_stream_command(Split),
             whole_stream_command(SplitColumn),
             whole_stream_command(SplitRow),
             whole_stream_command(Lines),
             whole_stream_command(Trim),
             whole_stream_command(Echo),
             whole_stream_command(Parse),
+            whole_stream_command(Str),
+            whole_stream_command(StrToDecimal),
+            whole_stream_command(StrToInteger),
+            whole_stream_command(StrDowncase),
+            whole_stream_command(StrUpcase),
+            whole_stream_command(StrCapitalize),
+            whole_stream_command(StrFindReplace),
+            whole_stream_command(StrSubstring),
+            whole_stream_command(StrSet),
+            whole_stream_command(StrToDatetime),
+            whole_stream_command(StrTrim),
+            whole_stream_command(BuildString),
             // Column manipulation
             whole_stream_command(Reject),
             whole_stream_command(Select),
@@ -297,6 +317,7 @@ pub fn create_default_context(
             whole_stream_command(Prepend),
             whole_stream_command(SortBy),
             whole_stream_command(GroupBy),
+            whole_stream_command(GroupByDate),
             whole_stream_command(First),
             whole_stream_command(Last),
             whole_stream_command(Nth),
@@ -324,6 +345,7 @@ pub fn create_default_context(
             whole_stream_command(Headers),
             // Data processing
             whole_stream_command(Histogram),
+            whole_stream_command(Average),
             whole_stream_command(Sum),
             // File format output
             whole_stream_command(To),
@@ -375,9 +397,7 @@ pub fn create_default_context(
 
         #[cfg(feature = "clipboard")]
         {
-            context.add_commands(vec![whole_stream_command(
+            context.add_commands(vec![whole_stream_command(crate::commands::clip::Clip)]);
-                crate::commands::clip::clipboard::Clip,
-            )]);
         }
     }
 
@@ -465,8 +485,8 @@ pub async fn run_pipeline_standalone(
         }
 
         LineResult::Error(line, err) => {
-            context.with_host(|host| {
+            context.with_host(|_host| {
-                print_err(err, host, &Text::from(line.clone()));
+                print_err(err, &Text::from(line.clone()));
             });
 
             context.maybe_print_errors(Text::from(line));
@@ -482,15 +502,15 @@ pub async fn run_pipeline_standalone(
 }
 
 /// The entry point for the CLI. Will register all known internal commands, load experimental commands, load plugins, then prepare the prompt and line reader for input.
-pub async fn cli() -> Result<(), Box<dyn Error>> {
+pub async fn cli(
+    mut syncer: EnvironmentSyncer,
+    mut context: Context,
+) -> Result<(), Box<dyn Error>> {
     #[cfg(windows)]
     const DEFAULT_COMPLETION_MODE: CompletionType = CompletionType::Circular;
     #[cfg(not(windows))]
     const DEFAULT_COMPLETION_MODE: CompletionType = CompletionType::List;
 
-    let mut syncer = crate::EnvironmentSyncer::new();
-    let mut context = create_default_context(&mut syncer, true)?;
-
     let _ = load_plugins(&mut context);
 
     let config = Config::builder().color_mode(ColorMode::Forced).build();
@@ -569,6 +589,13 @@ pub async fn cli() -> Result<(), Box<dyn Error>> {
 
         rl.set_edit_mode(edit_mode);
 
+        let max_history_size = config::config(Tag::unknown())?
+            .get("history_size")
+            .map(|i| i.value.expect_int())
+            .unwrap_or(100_000);
+
+        rl.set_max_history_size(max_history_size as usize);
+
         let key_timeout = config::config(Tag::unknown())?
             .get("key_timeout")
             .map(|s| s.value.expect_int())
@@ -591,6 +618,7 @@ pub async fn cli() -> Result<(), Box<dyn Error>> {
             #[cfg(feature = "starship-prompt")]
             {
                 std::env::set_var("STARSHIP_SHELL", "");
+                std::env::set_var("PWD", &cwd);
                 let mut starship_context =
                     starship::context::Context::new_with_dir(clap::ArgMatches::default(), cwd);
 
@@ -654,8 +682,8 @@ pub async fn cli() -> Result<(), Box<dyn Error>> {
                 rl.add_history_entry(line.clone());
                 let _ = rl.save_history(&History::path());
 
-                context.with_host(|host| {
+                context.with_host(|_host| {
-                    print_err(err, host, &Text::from(line.clone()));
+                    print_err(err, &Text::from(line.clone()));
                 });
 
                 context.maybe_print_errors(Text::from(line.clone()));
@@ -724,6 +752,7 @@ async fn process_line(
 
         Ok(line) => {
             let line = chomp_newline(line);
+            ctx.raw_input = line.to_string();
 
             let result = match nu_parser::lite_parse(&line, 0) {
                 Err(err) => {
@@ -860,7 +889,16 @@ async fn process_line(
 
             trace!("{:#?}", classified_block);
             let env = ctx.get_env();
-            match run_block(&classified_block.block, ctx, input_stream, &Scope::env(env)).await {
+            match run_block(
+                &classified_block.block,
+                ctx,
+                input_stream,
+                &Value::nothing(),
+                &IndexMap::new(),
+                &env,
+            )
+            .await
+            {
                 Ok(input) => {
                     // Running a pipeline gives us back a stream that we can then
                     // work through. At the top level, we just want to pull on the
@@ -872,11 +910,15 @@ async fn process_line(
                         shell_manager: ctx.shell_manager.clone(),
                         host: ctx.host.clone(),
                         ctrl_c: ctx.ctrl_c.clone(),
+                        current_errors: ctx.current_errors.clone(),
                         registry: ctx.registry.clone(),
                         name: Tag::unknown(),
+                        raw_input: line.to_string(),
                     };
 
-                    if let Ok(mut output_stream) = crate::commands::autoview::autoview(context) {
+                    if let Ok(mut output_stream) =
+                        crate::commands::autoview::autoview(context).await
+                    {
                         loop {
                             match output_stream.try_next().await {
                                 Ok(Some(ReturnSuccess::Value(Value {
@@ -908,19 +950,19 @@ async fn process_line(
     }
 }
 
-pub fn print_err(err: ShellError, host: &dyn Host, source: &Text) {
+pub fn print_err(err: ShellError, source: &Text) {
     if let Some(diag) = err.into_diagnostic() {
-        let writer = host.err_termcolor();
+        let source = source.to_string();
-        let mut source = source.to_string();
+        let mut files = codespan_reporting::files::SimpleFiles::new();
-        source.push_str(" ");
+        files.add("shell", source);
-        let files = nu_parser::Files::new(source);
+
+        let writer = codespan_reporting::term::termcolor::StandardStream::stderr(
+            codespan_reporting::term::termcolor::ColorChoice::Always,
+        );
+        let config = codespan_reporting::term::Config::default();
+
         let _ = std::panic::catch_unwind(move || {
-            let _ = language_reporting::emit(
+            let _ = codespan_reporting::term::emit(&mut writer.lock(), &config, &files, &diag);
-                &mut writer.lock(),
-                &files,
-                &diag,
-                &language_reporting::DefaultConfig,
-            );
         });
     }
 }

crates/nu-cli/src/commands.rs

@@ -8,10 +8,13 @@ pub(crate) mod alias;
 pub(crate) mod append;
 pub(crate) mod args;
 pub(crate) mod autoview;
+pub(crate) mod average;
+pub(crate) mod build_string;
 pub(crate) mod cal;
 pub(crate) mod calc;
 pub(crate) mod cd;
 pub(crate) mod classified;
+#[cfg(feature = "clipboard")]
 pub(crate) mod clip;
 pub(crate) mod command;
 pub(crate) mod compact;
@@ -50,6 +53,7 @@ pub(crate) mod from_xml;
 pub(crate) mod from_yaml;
 pub(crate) mod get;
 pub(crate) mod group_by;
+pub(crate) mod group_by_date;
 pub(crate) mod headers;
 pub(crate) mod help;
 pub(crate) mod histogram;
@@ -94,9 +98,9 @@ pub(crate) mod skip;
 pub(crate) mod skip_until;
 pub(crate) mod skip_while;
 pub(crate) mod sort_by;
+pub(crate) mod split;
 pub(crate) mod split_by;
-pub(crate) mod split_column;
+pub(crate) mod str_;
-pub(crate) mod split_row;
 pub(crate) mod sum;
 #[allow(unused)]
 pub(crate) mod t_sort_by;
@@ -131,6 +135,8 @@ pub(crate) use command::{
 
 pub(crate) use alias::Alias;
 pub(crate) use append::Append;
+pub(crate) use average::Average;
+pub(crate) use build_string::BuildString;
 pub(crate) use cal::Cal;
 pub(crate) use calc::Calc;
 pub(crate) use compact::Compact;
@@ -178,6 +184,7 @@ pub(crate) use from_yaml::FromYAML;
 pub(crate) use from_yaml::FromYML;
 pub(crate) use get::Get;
 pub(crate) use group_by::GroupBy;
+pub(crate) use group_by_date::GroupByDate;
 pub(crate) use headers::Headers;
 pub(crate) use help::Help;
 pub(crate) use histogram::Histogram;
@@ -219,9 +226,14 @@ pub(crate) use skip::Skip;
 pub(crate) use skip_until::SkipUntil;
 pub(crate) use skip_while::SkipWhile;
 pub(crate) use sort_by::SortBy;
+pub(crate) use split::Split;
+pub(crate) use split::SplitColumn;
+pub(crate) use split::SplitRow;
 pub(crate) use split_by::SplitBy;
-pub(crate) use split_column::SplitColumn;
+pub(crate) use str_::{
-pub(crate) use split_row::SplitRow;
+    Str, StrCapitalize, StrDowncase, StrFindReplace, StrSet, StrSubstring, StrToDatetime,
+    StrToDecimal, StrToInteger, StrTrim, StrUpcase,
+};
 pub(crate) use sum::Sum;
 #[allow(unused_imports)]
 pub(crate) use t_sort_by::TSortBy;

crates/nu-cli/src/commands/alias.rs

@@ -1,8 +1,11 @@
 use crate::commands::WholeStreamCommand;
 use crate::context::CommandRegistry;
+use crate::data::config;
 use crate::prelude::*;
 use nu_errors::ShellError;
-use nu_protocol::{hir::Block, CommandAction, ReturnSuccess, Signature, SyntaxShape, Value};
+use nu_protocol::{
+    hir::Block, CommandAction, ReturnSuccess, Signature, SyntaxShape, UntaggedValue, Value,
+};
 use nu_source::Tagged;
 
 pub struct Alias;
@@ -12,8 +15,10 @@ pub struct AliasArgs {
     pub name: Tagged<String>,
     pub args: Vec<Value>,
     pub block: Block,
+    pub save: Option<bool>,
 }
 
+#[async_trait]
 impl WholeStreamCommand for Alias {
     fn name(&self) -> &str {
         "alias"
@@ -28,53 +33,105 @@ impl WholeStreamCommand for Alias {
                 SyntaxShape::Block,
                 "the block to run as the body of the alias",
             )
+            .switch("save", "save the alias to your config", Some('s'))
     }
 
     fn usage(&self) -> &str {
         "Define a shortcut for another command."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, alias)?.run()
+        // args.process(registry, alias)?.run()
+        alias(args, registry)
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[
+        vec![
             Example {
                 description: "An alias without parameters",
                 example: "alias say-hi [] { echo 'Hello!' }",
+                result: None,
             },
             Example {
                 description: "An alias with a single parameter",
                 example: "alias l [x] { ls $x }",
+                result: None,
             },
         ]
     }
 }
 
-pub fn alias(
+// <<<<<<< HEAD
-    AliasArgs {
+// pub fn alias(alias_args: AliasArgs, ctx: RunnableContext) -> Result<OutputStream, ShellError> {
-        name,
+// =======
-        args: list,
+pub fn alias(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
-        block,
+    let registry = registry.clone();
-    }: AliasArgs,
-    _: RunnableContext,
-) -> Result<OutputStream, ShellError> {
     let stream = async_stream! {
-        let mut args: Vec<String> = vec![];
+        let mut raw_input = args.raw_input.clone();
+        let (AliasArgs { name, args: list, block, save}, ctx) = args.process(&registry).await?;
+        let mut processed_args: Vec<String> = vec![];
+
+        if let Some(true) = save {
+            let mut result = crate::data::config::read(name.clone().tag, &None)?;
+
+            // process the alias to remove the --save flag
+            let left_brace = raw_input.find('{').unwrap_or(0);
+            let right_brace = raw_input.rfind('}').unwrap_or(raw_input.len());
+            let mut left = raw_input[..left_brace].replace("--save", "").replace("-s", "");
+            let mut right = raw_input[right_brace..].replace("--save", "").replace("-s", "");
+            raw_input = format!("{}{}{}", left, &raw_input[left_brace..right_brace], right);
+
+            // create a value from raw_input alias
+            let alias: Value = raw_input.trim().to_string().into();
+            let alias_start = raw_input.find("[").unwrap_or(0); // used to check if the same alias already exists
+
+            // add to startup if alias doesn't exist and replce if it does
+            match result.get_mut("startup") {
+                Some(startup) => {
+                    if let UntaggedValue::Table(ref mut commands) = startup.value {
+                        if let Some(command) = commands.iter_mut().find(|command| {
+                            let cmd_str = command.as_string().unwrap_or_default();
+                            cmd_str.starts_with(&raw_input[..alias_start])
+                        }) {
+                            *command = alias;
+                        } else {
+                            commands.push(alias);
+                        }
+                    }
+                }
+                None => {
+                    let mut table = UntaggedValue::table(&[alias]);
+                    result.insert("startup".to_string(), table.into_value(Tag::default()));
+                }
+            }
+            config::write(&result, &None)?;
+        }
+
         for item in list.iter() {
             if let Ok(string) = item.as_string() {
-                args.push(format!("${}", string));
+                processed_args.push(format!("${}", string));
             } else {
                 yield Err(ShellError::labeled_error("Expected a string", "expected a string", item.tag()));
             }
         }
-        yield ReturnSuccess::action(CommandAction::AddAlias(name.to_string(), args, block.clone()))
+        yield ReturnSuccess::action(CommandAction::AddAlias(name.to_string(), processed_args, block.clone()))
     };
 
     Ok(stream.to_output_stream())
 }
+
+#[cfg(test)]
+mod tests {
+    use super::Alias;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Alias {})
+    }
+}

crates/nu-cli/src/commands/append.rs

@@ -2,7 +2,7 @@ use crate::commands::WholeStreamCommand;
 use crate::context::CommandRegistry;
 use crate::prelude::*;
 use nu_errors::ShellError;
-use nu_protocol::{Signature, SyntaxShape, Value};
+use nu_protocol::{Signature, SyntaxShape, UntaggedValue, Value};
 
 #[derive(Deserialize)]
 struct AppendArgs {
@@ -11,6 +11,7 @@ struct AppendArgs {
 
 pub struct Append;
 
+#[async_trait]
 impl WholeStreamCommand for Append {
     fn name(&self) -> &str {
         "append"
@@ -28,29 +29,40 @@ impl WholeStreamCommand for Append {
         "Append the given row to the table"
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, append)?.run()
+        let (AppendArgs { row }, input) = args.process(registry).await?;
+
+        let eos = futures::stream::iter(vec![row]);
+
+        Ok(input.chain(eos).to_output_stream())
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[Example {
+        vec![Example {
             description: "Add something to the end of a list or table",
             example: "echo [1 2 3] | append 4",
+            result: Some(vec![
+                UntaggedValue::int(1).into(),
+                UntaggedValue::int(2).into(),
+                UntaggedValue::int(3).into(),
+                UntaggedValue::int(4).into(),
+            ]),
         }]
     }
 }
 
-fn append(
+#[cfg(test)]
-    AppendArgs { row }: AppendArgs,
+mod tests {
-    RunnableContext { input, .. }: RunnableContext,
+    use super::Append;
-) -> Result<OutputStream, ShellError> {
-    let mut after: VecDeque<Value> = VecDeque::new();
-    after.push_back(row);
-    let after = futures::stream::iter(after);
 
-    Ok(OutputStream::from_input(input.chain(after)))
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Append {})
+    }
 }

crates/nu-cli/src/commands/autoview.rs

@@ -4,12 +4,17 @@ use crate::data::value::format_leaf;
 use crate::prelude::*;
 use nu_errors::ShellError;
 use nu_protocol::{hir, hir::Expression, hir::Literal, hir::SpannedExpression};
-use nu_protocol::{Primitive, ReturnSuccess, Scope, Signature, UntaggedValue, Value};
+use nu_protocol::{Primitive, Scope, Signature, UntaggedValue, Value};
+use parking_lot::Mutex;
+use prettytable::format::{FormatBuilder, LinePosition, LineSeparator};
+use prettytable::{color, Attr, Cell, Row, Table};
 use std::sync::atomic::AtomicBool;
 use std::sync::atomic::Ordering;
+use textwrap::fill;
 
 pub struct Autoview;
 
+#[async_trait]
 impl WholeStreamCommand for Autoview {
     fn name(&self) -> &str {
         "autoview"
@@ -23,7 +28,7 @@ impl WholeStreamCommand for Autoview {
         "View the contents of the pipeline as a table or list."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
@@ -34,19 +39,24 @@ impl WholeStreamCommand for Autoview {
             shell_manager: args.shell_manager,
             host: args.host,
             ctrl_c: args.ctrl_c,
+            current_errors: args.current_errors,
             name: args.call_info.name_tag,
+            raw_input: args.raw_input,
         })
+        .await
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[
+        vec![
             Example {
                 description: "Automatically view the results",
                 example: "ls | autoview",
+                result: None,
             },
             Example {
                 description: "Autoview is also implied. The above can be written as",
                 example: "ls",
+                result: None,
             },
         ]
     }
@@ -55,6 +65,7 @@ impl WholeStreamCommand for Autoview {
 pub struct RunnableContextWithoutInput {
     pub shell_manager: ShellManager,
     pub host: Arc<parking_lot::Mutex<Box<dyn Host>>>,
+    pub current_errors: Arc<Mutex<Vec<ShellError>>>,
     pub ctrl_c: Arc<AtomicBool>,
     pub registry: CommandRegistry,
     pub name: Tag,
@@ -66,6 +77,7 @@ impl RunnableContextWithoutInput {
             shell_manager: context.shell_manager,
             host: context.host,
             ctrl_c: context.ctrl_c,
+            current_errors: context.current_errors,
             registry: context.registry,
             name: context.name,
         };
@@ -73,241 +85,307 @@ impl RunnableContextWithoutInput {
     }
 }
 
-pub fn autoview(context: RunnableContext) -> Result<OutputStream, ShellError> {
+pub async fn autoview(context: RunnableContext) -> Result<OutputStream, ShellError> {
     let binary = context.get_command("binaryview");
     let text = context.get_command("textview");
     let table = context.get_command("table");
 
-    Ok(OutputStream::new(async_stream! {
+    #[derive(PartialEq)]
-        let (mut input_stream, context) = RunnableContextWithoutInput::convert(context);
+    enum AutoPivotMode {
+        Auto,
+        Always,
+        Never,
+    }
 
+    let pivot_mode = crate::data::config::config(Tag::unknown());
+    let pivot_mode = if let Some(v) = pivot_mode?.get("pivot_mode") {
+        match v.as_string() {
+            Ok(m) if m.to_lowercase() == "auto" => AutoPivotMode::Auto,
+            Ok(m) if m.to_lowercase() == "always" => AutoPivotMode::Always,
+            Ok(m) if m.to_lowercase() == "never" => AutoPivotMode::Never,
+            _ => AutoPivotMode::Always,
+        }
+    } else {
+        AutoPivotMode::Always
+    };
+
+    let (mut input_stream, context) = RunnableContextWithoutInput::convert(context);
+
+    if let Some(x) = input_stream.next().await {
         match input_stream.next().await {
-            Some(x) => {
+            Some(y) => {
-                match input_stream.next().await {
+                let ctrl_c = context.ctrl_c.clone();
-                    Some(y) => {
+                let stream = async_stream! {
-                        let ctrl_c = context.ctrl_c.clone();
+                    yield Ok(x);
-                        let stream = async_stream! {
+                    yield Ok(y);
-                            yield Ok(x);
-                            yield Ok(y);
 
-                            loop {
+                    loop {
-                                match input_stream.next().await {
+                        match input_stream.next().await {
-                                    Some(z) => {
+                            Some(z) => {
-                                        if ctrl_c.load(Ordering::SeqCst) {
+                                if ctrl_c.load(Ordering::SeqCst) {
-                                            break;
+                                    break;
-                                        }
-                                        yield Ok(z);
-                                    }
-                                    _ => break,
                                 }
+                                yield Ok(z);
                             }
-                        };
+                            _ => break,
-                        let stream = stream.to_input_stream();
-
-                        if let Some(table) = table {
-                            let command_args = create_default_command_args(&context).with_input(stream);
-                            let result = table.run(command_args, &context.registry);
-                            result.collect::<Vec<_>>().await;
                         }
                     }
-                    _ => {
+                };
-                        match x {
+                let stream = stream.to_input_stream();
-                            Value {
-                                value: UntaggedValue::Primitive(Primitive::String(ref s)),
-                                tag: Tag { anchor, span },
-                            } if anchor.is_some() => {
-                                if let Some(text) = text {
-                                    let mut stream = VecDeque::new();
-                                    stream.push_back(UntaggedValue::string(s).into_value(Tag { anchor, span }));
-                                    let command_args = create_default_command_args(&context).with_input(stream);
-                                    let result = text.run(command_args, &context.registry);
-                                    result.collect::<Vec<_>>().await;
-                                } else {
-                                    out!("{}", s);
-                                }
-                            }
-                            Value {
-                                value: UntaggedValue::Primitive(Primitive::String(s)),
-                                ..
-                            } => {
-                                out!("{}", s);
-                            }
-                            Value {
-                                value: UntaggedValue::Primitive(Primitive::Line(ref s)),
-                                tag: Tag { anchor, span },
-                            } if anchor.is_some() => {
-                                if let Some(text) = text {
-                                    let mut stream = VecDeque::new();
-                                    stream.push_back(UntaggedValue::string(s).into_value(Tag { anchor, span }));
-                                    let command_args = create_default_command_args(&context).with_input(stream);
-                                    let result = text.run(command_args, &context.registry);
-                                    result.collect::<Vec<_>>().await;
-                                } else {
-                                    out!("{}\n", s);
-                                }
-                            }
-                            Value {
-                                value: UntaggedValue::Primitive(Primitive::Line(s)),
-                                ..
-                            } => {
-                                out!("{}\n", s);
-                            }
-                            Value {
-                                value: UntaggedValue::Primitive(Primitive::Path(s)),
-                                ..
-                            } => {
-                                out!("{}", s.display());
-                            }
-                            Value {
-                                value: UntaggedValue::Primitive(Primitive::Int(n)),
-                                ..
-                            } => {
-                                out!("{}", n);
-                            }
-                            Value {
-                                value: UntaggedValue::Primitive(Primitive::Decimal(n)),
-                                ..
-                            } => {
-                                out!("{}", n);
-                            }
-                            Value {
-                                value: UntaggedValue::Primitive(Primitive::Boolean(b)),
-                                ..
-                            } => {
-                                out!("{}", b);
-                            }
-                            Value {
-                                value: UntaggedValue::Primitive(Primitive::Duration(d)),
-                                ..
-                            } => {
-                                let output = format_leaf(&x).plain_string(100_000);
-                                out!("{}", output);
-                            }
-                            Value {
-                                value: UntaggedValue::Primitive(Primitive::Date(d)),
-                                ..
-                            } => {
-                                out!("{}", d);
-                            }
-                            Value {
-                                value: UntaggedValue::Primitive(Primitive::Range(_)),
-                                ..
-                            } => {
-                                let output = format_leaf(&x).plain_string(100_000);
-                                out!("{}", output);
-                            }
 
-                            Value { value: UntaggedValue::Primitive(Primitive::Binary(ref b)), .. } => {
+                if let Some(table) = table {
-                                if let Some(binary) = binary {
+                    let command_args = create_default_command_args(&context).with_input(stream);
-                                    let mut stream = VecDeque::new();
+                    let result = table.run(command_args, &context.registry).await;
-                                    stream.push_back(x);
+                    result.collect::<Vec<_>>().await;
-                                    let command_args = create_default_command_args(&context).with_input(stream);
+                }
-                                    let result = binary.run(command_args, &context.registry);
+            }
-                                    result.collect::<Vec<_>>().await;
+            _ => {
-                                } else {
+                match x {
-                                    use pretty_hex::*;
+                    Value {
-                                    out!("{:?}", b.hex_dump());
+                        value: UntaggedValue::Primitive(Primitive::String(ref s)),
-                                }
+                        tag: Tag { anchor, span },
+                    } if anchor.is_some() => {
+                        if let Some(text) = text {
+                            let mut stream = VecDeque::new();
+                            stream.push_back(
+                                UntaggedValue::string(s).into_value(Tag { anchor, span }),
+                            );
+                            let command_args =
+                                create_default_command_args(&context).with_input(stream);
+                            let result = text.run(command_args, &context.registry).await;
+                            result.collect::<Vec<_>>().await;
+                        } else {
+                            out!("{}", s);
+                        }
+                    }
+                    Value {
+                        value: UntaggedValue::Primitive(Primitive::String(s)),
+                        ..
+                    } => {
+                        out!("{}", s);
+                    }
+                    Value {
+                        value: UntaggedValue::Primitive(Primitive::Line(ref s)),
+                        tag: Tag { anchor, span },
+                    } if anchor.is_some() => {
+                        if let Some(text) = text {
+                            let mut stream = VecDeque::new();
+                            stream.push_back(
+                                UntaggedValue::string(s).into_value(Tag { anchor, span }),
+                            );
+                            let command_args =
+                                create_default_command_args(&context).with_input(stream);
+                            let result = text.run(command_args, &context.registry).await;
+                            result.collect::<Vec<_>>().await;
+                        } else {
+                            out!("{}\n", s);
+                        }
+                    }
+                    Value {
+                        value: UntaggedValue::Primitive(Primitive::Line(s)),
+                        ..
+                    } => {
+                        out!("{}\n", s);
+                    }
+                    Value {
+                        value: UntaggedValue::Primitive(Primitive::Path(s)),
+                        ..
+                    } => {
+                        out!("{}", s.display());
+                    }
+                    Value {
+                        value: UntaggedValue::Primitive(Primitive::Int(n)),
+                        ..
+                    } => {
+                        out!("{}", n);
+                    }
+                    Value {
+                        value: UntaggedValue::Primitive(Primitive::Decimal(n)),
+                        ..
+                    } => {
+                        // TODO: normalize decimal to remove trailing zeros.
+                        // normalization will be available in next release of bigdecimal crate
+                        let mut output = n.to_string();
+                        if output.contains('.') {
+                            output = output.trim_end_matches('0').to_owned();
+                        }
+                        if output.ends_with('.') {
+                            output.push('0');
+                        }
+                        out!("{}", output);
+                    }
+                    Value {
+                        value: UntaggedValue::Primitive(Primitive::Boolean(b)),
+                        ..
+                    } => {
+                        out!("{}", b);
+                    }
+                    Value {
+                        value: UntaggedValue::Primitive(Primitive::Duration(_)),
+                        ..
+                    } => {
+                        let output = format_leaf(&x).plain_string(100_000);
+                        out!("{}", output);
+                    }
+                    Value {
+                        value: UntaggedValue::Primitive(Primitive::Date(d)),
+                        ..
+                    } => {
+                        out!("{}", d);
+                    }
+                    Value {
+                        value: UntaggedValue::Primitive(Primitive::Range(_)),
+                        ..
+                    } => {
+                        let output = format_leaf(&x).plain_string(100_000);
+                        out!("{}", output);
+                    }
+
+                    Value {
+                        value: UntaggedValue::Primitive(Primitive::Binary(ref b)),
+                        ..
+                    } => {
+                        if let Some(binary) = binary {
+                            let mut stream = VecDeque::new();
+                            stream.push_back(x);
+                            let command_args =
+                                create_default_command_args(&context).with_input(stream);
+                            let result = binary.run(command_args, &context.registry).await;
+                            result.collect::<Vec<_>>().await;
+                        } else {
+                            use pretty_hex::*;
+                            out!("{:?}", b.hex_dump());
+                        }
+                    }
+
+                    Value {
+                        value: UntaggedValue::Error(e),
+                        ..
+                    } => {
+                        return Err(e);
+                    }
+
+                    Value {
+                        value: UntaggedValue::Row(row),
+                        ..
+                    } if pivot_mode == AutoPivotMode::Always
+                        || (pivot_mode == AutoPivotMode::Auto
+                            && (row
+                                .entries
+                                .iter()
+                                .map(|(_, v)| v.convert_to_string())
+                                .collect::<Vec<_>>()
+                                .iter()
+                                .fold(0usize, |acc, len| acc + len.len())
+                                + row.entries.iter().count() * 2)
+                                > textwrap::termwidth()) =>
+                    {
+                        let termwidth = std::cmp::max(textwrap::termwidth(), 20);
+
+                        enum TableMode {
+                            Light,
+                            Normal,
+                        }
+
+                        let mut table = Table::new();
+                        let table_mode = crate::data::config::config(Tag::unknown());
+
+                        let table_mode = if let Some(s) = table_mode?.get("table_mode") {
+                            match s.as_string() {
+                                Ok(typ) if typ == "light" => TableMode::Light,
+                                _ => TableMode::Normal,
                             }
+                        } else {
+                            TableMode::Normal
+                        };
 
-                            Value { value: UntaggedValue::Error(e), .. } => {
+                        match table_mode {
-                                yield Err(e);
+                            TableMode::Light => {
+                                table.set_format(
+                                    FormatBuilder::new()
+                                        .separator(
+                                            LinePosition::Title,
+                                            LineSeparator::new('─', '─', ' ', ' '),
+                                        )
+                                        .separator(
+                                            LinePosition::Bottom,
+                                            LineSeparator::new(' ', ' ', ' ', ' '),
+                                        )
+                                        .padding(1, 1)
+                                        .build(),
+                                );
                             }
-
+                            _ => {
-                            Value { value: UntaggedValue::Row(row), ..} => {
+                                table.set_format(
-                                use prettytable::format::{FormatBuilder, LinePosition, LineSeparator};
+                                    FormatBuilder::new()
-                                use prettytable::{color, Attr, Cell, Row, Table};
+                                        .column_separator('│')
-                                use crate::data::value::{format_leaf, style_leaf};
+                                        .separator(
-                                use textwrap::fill;
+                                            LinePosition::Top,
-
+                                            LineSeparator::new('─', '┬', ' ', ' '),
-                                let termwidth = std::cmp::max(textwrap::termwidth(), 20);
+                                        )
-
+                                        .separator(
-                                enum TableMode {
+                                            LinePosition::Title,
-                                    Light,
+                                            LineSeparator::new('─', '┼', ' ', ' '),
-                                    Normal,
+                                        )
-                                }
+                                        .separator(
-
+                                            LinePosition::Bottom,
-                                let mut table = Table::new();
+                                            LineSeparator::new('─', '┴', ' ', ' '),
-                                let table_mode = crate::data::config::config(Tag::unknown());
+                                        )
-
+                                        .padding(1, 1)
-                                let table_mode = if let Some(s) = table_mode?.get("table_mode") {
+                                        .build(),
-                                    match s.as_string() {
+                                );
-                                        Ok(typ) if typ == "light" => TableMode::Light,
-                                        _ => TableMode::Normal,
-                                    }
-                                } else {
-                                    TableMode::Normal
-                                };
-
-                                match table_mode {
-                                    TableMode::Light => {
-                                        table.set_format(
-                                            FormatBuilder::new()
-                                                .separator(LinePosition::Title, LineSeparator::new('─', '─', ' ', ' '))
-                                                .padding(1, 1)
-                                                .build(),
-                                        );
-                                    }
-                                    _ => {
-                                        table.set_format(
-                                            FormatBuilder::new()
-                                                .column_separator('│')
-                                                .separator(LinePosition::Top, LineSeparator::new('─', '┬', ' ', ' '))
-                                                .separator(LinePosition::Title, LineSeparator::new('─', '┼', ' ', ' '))
-                                                .separator(LinePosition::Bottom, LineSeparator::new('─', '┴', ' ', ' '))
-                                                .padding(1, 1)
-                                                .build(),
-                                        );
-                                    }
-                                }
-
-                                let mut max_key_len = 0;
-                                for (key, _) in row.entries.iter() {
-                                    max_key_len = std::cmp::max(max_key_len, key.chars().count());
-                                }
-
-                                if max_key_len > (termwidth/2 - 1) {
-                                    max_key_len = termwidth/2 - 1;
-                                }
-
-                                let max_val_len = termwidth - max_key_len - 5;
-
-                                for (key, value) in row.entries.iter() {
-                                    table.add_row(Row::new(vec![Cell::new(&fill(&key, max_key_len)).with_style(Attr::ForegroundColor(color::GREEN)).with_style(Attr::Bold),
-                                        Cell::new(&fill(&format_leaf(value).plain_string(100_000), max_val_len))]));
-                                }
-
-                                table.printstd();
-
-                                // table.print_term(&mut *context.host.lock().out_terminal().ok_or_else(|| ShellError::untagged_runtime_error("Could not open terminal for output"))?)
-                                //     .map_err(|_| ShellError::untagged_runtime_error("Internal error: could not print to terminal (for unix systems check to make sure TERM is set)"))?;
                             }
+                        }
 
-                            Value { value: ref item, .. } => {
+                        let mut max_key_len = 0;
-                                if let Some(table) = table {
+                        for (key, _) in row.entries.iter() {
-                                    let mut stream = VecDeque::new();
+                            max_key_len = std::cmp::max(max_key_len, key.chars().count());
-                                    stream.push_back(x);
+                        }
-                                    let command_args = create_default_command_args(&context).with_input(stream);
+
-                                    let result = table.run(command_args, &context.registry);
+                        if max_key_len > (termwidth / 2 - 1) {
-                                    result.collect::<Vec<_>>().await;
+                            max_key_len = termwidth / 2 - 1;
-                                } else {
+                        }
-                                    out!("{:?}", item);
+
-                                }
+                        let max_val_len = termwidth - max_key_len - 5;
-                            }
+
+                        for (key, value) in row.entries.iter() {
+                            table.add_row(Row::new(vec![
+                                Cell::new(&fill(&key, max_key_len))
+                                    .with_style(Attr::ForegroundColor(color::GREEN))
+                                    .with_style(Attr::Bold),
+                                Cell::new(&fill(
+                                    &format_leaf(value).plain_string(100_000),
+                                    max_val_len,
+                                )),
+                            ]));
+                        }
+
+                        table.printstd();
+
+                        // table.print_term(&mut *context.host.lock().out_terminal().ok_or_else(|| ShellError::untagged_runtime_error("Could not open terminal for output"))?)
+                        //     .map_err(|_| ShellError::untagged_runtime_error("Internal error: could not print to terminal (for unix systems check to make sure TERM is set)"))?;
+                    }
+
+                    Value {
+                        value: ref item, ..
+                    } => {
+                        if let Some(table) = table {
+                            let mut stream = VecDeque::new();
+                            stream.push_back(x);
+                            let command_args =
+                                create_default_command_args(&context).with_input(stream);
+                            let result = table.run(command_args, &context.registry).await;
+                            result.collect::<Vec<_>>().await;
+                        } else {
+                            out!("{:?}", item);
                         }
                     }
                 }
             }
-            _ => {
-                //out!("<no results>");
-            }
         }
+    }
 
-        // Needed for async_stream to type check
+    Ok(OutputStream::empty())
-        if false {
-            yield ReturnSuccess::value(UntaggedValue::nothing().into_untagged_value());
-        }
-    }))
 }
 
 fn create_default_command_args(context: &RunnableContextWithoutInput) -> RawCommandArgs {
@@ -315,6 +393,7 @@ fn create_default_command_args(context: &RunnableContextWithoutInput) -> RawComm
     RawCommandArgs {
         host: context.host.clone(),
         ctrl_c: context.ctrl_c.clone(),
+        current_errors: context.current_errors.clone(),
         shell_manager: context.shell_manager.clone(),
         call_info: UnevaluatedCallInfo {
             args: hir::Call {
@@ -328,7 +407,19 @@ fn create_default_command_args(context: &RunnableContextWithoutInput) -> RawComm
                 is_last: true,
             },
             name_tag: context.name.clone(),
-            scope: Scope::empty(),
+            scope: Scope::new(),
         },
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::Autoview;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Autoview {})
+    }
+}

crates/nu-cli/src/commands/average.rs

@@ -0,0 +1,173 @@
+use crate::commands::WholeStreamCommand;
+use crate::prelude::*;
+use crate::utils::data_processing::{reducer_for, Reduce};
+use bigdecimal::FromPrimitive;
+use nu_errors::ShellError;
+use nu_protocol::hir::{convert_number_to_u64, Number, Operator};
+use nu_protocol::{
+    Dictionary, Primitive, ReturnSuccess, ReturnValue, Signature, UntaggedValue, Value,
+};
+use num_traits::identities::Zero;
+
+use indexmap::map::IndexMap;
+
+pub struct Average;
+
+#[async_trait]
+impl WholeStreamCommand for Average {
+    fn name(&self) -> &str {
+        "average"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("average")
+    }
+
+    fn usage(&self) -> &str {
+        "Average the values."
+    }
+
+    async fn run(
+        &self,
+        args: CommandArgs,
+        registry: &CommandRegistry,
+    ) -> Result<OutputStream, ShellError> {
+        average(RunnableContext {
+            input: args.input,
+            registry: registry.clone(),
+            shell_manager: args.shell_manager,
+            host: args.host,
+            ctrl_c: args.ctrl_c,
+            current_errors: args.current_errors,
+            name: args.call_info.name_tag,
+            raw_input: args.raw_input,
+        })
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![Example {
+            description: "Average a list of numbers",
+            example: "echo [100 0 100 0] | average",
+            result: Some(vec![UntaggedValue::decimal(50).into()]),
+        }]
+    }
+}
+
+fn average(
+    RunnableContext {
+        mut input, name, ..
+    }: RunnableContext,
+) -> Result<OutputStream, ShellError> {
+    let stream = async_stream! {
+        let mut values: Vec<Value> = input.drain_vec().await;
+        let action = reducer_for(Reduce::Sum);
+
+        if values.iter().all(|v| if let UntaggedValue::Primitive(_) = v.value {true} else {false}) {
+            match avg(&values, name) {
+                Ok(result) => yield ReturnSuccess::value(result),
+                Err(err) => yield Err(err),
+            }
+        } else {
+            let mut column_values = IndexMap::new();
+            for value in values {
+                match value.value {
+                    UntaggedValue::Row(row_dict) => {
+                        for (key, value) in row_dict.entries.iter() {
+                            column_values
+                                .entry(key.clone())
+                                .and_modify(|v: &mut Vec<Value>| v.push(value.clone()))
+                                .or_insert(vec![value.clone()]);
+                        }
+                    },
+                    table => {},
+                };
+            }
+
+            let mut column_totals = IndexMap::new();
+            for (col_name, col_vals) in column_values {
+                match avg(&col_vals, &name) {
+                    Ok(result) => {
+                        column_totals.insert(col_name, result);
+                    }
+                    Err(err) => yield Err(err),
+                }
+            }
+            yield ReturnSuccess::value(
+                UntaggedValue::Row(Dictionary {entries: column_totals}).into_untagged_value())
+        }
+    };
+
+    let stream: BoxStream<'static, ReturnValue> = stream.boxed();
+
+    Ok(stream.to_output_stream())
+}
+
+fn avg(values: &[Value], name: impl Into<Tag>) -> Result<Value, ShellError> {
+    let name = name.into();
+
+    let sum = reducer_for(Reduce::Sum);
+
+    let number = BigDecimal::from_usize(values.len()).expect("expected a usize-sized bigdecimal");
+
+    let total_rows = UntaggedValue::decimal(number);
+    let total = sum(Value::zero(), values.to_vec())?;
+
+    match total {
+        Value {
+            value: UntaggedValue::Primitive(Primitive::Bytes(num)),
+            ..
+        } => {
+            let left = UntaggedValue::from(Primitive::Int(num.into()));
+            let result = crate::data::value::compute_values(Operator::Divide, &left, &total_rows);
+
+            match result {
+                Ok(UntaggedValue::Primitive(Primitive::Decimal(result))) => {
+                    let number = Number::Decimal(result);
+                    let number = convert_number_to_u64(&number);
+                    Ok(UntaggedValue::bytes(number).into_value(name))
+                }
+                Ok(_) => Err(ShellError::labeled_error(
+                    "could not calculate average of non-integer or unrelated types",
+                    "source",
+                    name,
+                )),
+                Err((left_type, right_type)) => Err(ShellError::coerce_error(
+                    left_type.spanned(name.span),
+                    right_type.spanned(name.span),
+                )),
+            }
+        }
+        Value {
+            value: UntaggedValue::Primitive(other),
+            ..
+        } => {
+            let left = UntaggedValue::from(other);
+            let result = crate::data::value::compute_values(Operator::Divide, &left, &total_rows);
+
+            match result {
+                Ok(value) => Ok(value.into_value(name)),
+                Err((left_type, right_type)) => Err(ShellError::coerce_error(
+                    left_type.spanned(name.span),
+                    right_type.spanned(name.span),
+                )),
+            }
+        }
+        _ => Err(ShellError::labeled_error(
+            "could not calculate average of non-integer or unrelated types",
+            "source",
+            name,
+        )),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Average;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Average {})
+    }
+}

crates/nu-cli/src/commands/build_string.rs

@@ -0,0 +1,56 @@
+use crate::prelude::*;
+use nu_errors::ShellError;
+
+use crate::commands::WholeStreamCommand;
+use crate::data::value::format_leaf;
+use nu_protocol::{ReturnSuccess, Signature, SyntaxShape, UntaggedValue, Value};
+
+#[derive(Deserialize)]
+pub struct BuildStringArgs {
+    rest: Vec<Value>,
+}
+
+pub struct BuildString;
+
+#[async_trait]
+impl WholeStreamCommand for BuildString {
+    fn name(&self) -> &str {
+        "build-string"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("build-string")
+            .rest(SyntaxShape::Any, "all values to form into the string")
+    }
+
+    fn usage(&self) -> &str {
+        "Builds a string from the arguments"
+    }
+
+    async fn run(
+        &self,
+        args: CommandArgs,
+        registry: &CommandRegistry,
+    ) -> Result<OutputStream, ShellError> {
+        let tag = args.call_info.name_tag.clone();
+        let (BuildStringArgs { rest }, _) = args.process(&registry).await?;
+
+        let mut output_string = String::new();
+
+        for r in rest {
+            output_string.push_str(&format_leaf(&r).plain_string(100_000))
+        }
+
+        Ok(OutputStream::one(ReturnSuccess::value(
+            UntaggedValue::string(output_string).into_value(tag),
+        )))
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![Example {
+            description: "Builds a string from a string and a number, without spaces between them",
+            example: "build-string 'foo' 3",
+            result: None,
+        }]
+    }
+}

crates/nu-cli/src/commands/cal.rs

@@ -1,14 +1,13 @@
-use crate::prelude::*;
-use chrono::{DateTime, Datelike, Local, NaiveDate};
-use nu_errors::ShellError;
-use nu_protocol::Dictionary;
-
 use crate::commands::{command::EvaluatedWholeStreamCommandArgs, WholeStreamCommand};
+use crate::prelude::*;
+use chrono::{Datelike, Local, NaiveDate};
 use indexmap::IndexMap;
-use nu_protocol::{Signature, SyntaxShape, UntaggedValue, Value};
+use nu_errors::ShellError;
+use nu_protocol::{Dictionary, Signature, SyntaxShape, UntaggedValue, Value};
 
 pub struct Cal;
 
+#[async_trait]
 impl WholeStreamCommand for Cal {
     fn name(&self) -> &str {
         "cal"
@@ -36,104 +35,190 @@ impl WholeStreamCommand for Cal {
         "Display a calendar."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        cal(args, registry)
+        cal(args, registry).await
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[
+        vec![
             Example {
                 description: "This month's calendar",
                 example: "cal",
+                result: None,
             },
             Example {
                 description: "The calendar for all of 2012",
                 example: "cal --full-year 2012",
+                result: None,
             },
         ]
     }
 }
 
-pub fn cal(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
+pub async fn cal(
-    let args = args.evaluate_once(registry)?;
+    args: CommandArgs,
+    registry: &CommandRegistry,
+) -> Result<OutputStream, ShellError> {
+    let registry = registry.clone();
+    let args = args.evaluate_once(&registry).await?;
     let mut calendar_vec_deque = VecDeque::new();
     let tag = args.call_info.name_tag.clone();
 
     let (current_year, current_month, current_day) = get_current_date();
 
-    if args.has("full-year") {
+    let mut selected_year: i32 = current_year;
-        let mut day_value: Option<u32> = Some(current_day);
+    let mut current_day_option: Option<u32> = Some(current_day);
-        let mut year_value = current_year as u64;
 
-        if let Some(year) = args.get("full-year") {
+    let month_range = if args.has("full-year") {
-            if let Ok(year_u64) = year.as_u64() {
+        if let Some(full_year_value) = args.get("full-year") {
-                year_value = year_u64;
+            if let Ok(year_u64) = full_year_value.as_u64() {
-            }
+                selected_year = year_u64 as i32;
 
-            if year_value != current_year as u64 {
+                if selected_year != current_year {
-                day_value = None
+                    current_day_option = None
+                }
+            } else {
+                return Err(get_invalid_year_shell_error(&full_year_value.tag()));
             }
         }
 
-        add_year_to_table(
+        (1, 12)
-            &mut calendar_vec_deque,
-            &tag,
-            year_value as i32,
-            current_year,
-            current_month,
-            day_value,
-            &args,
-        );
     } else {
-        let (day_start_offset, number_of_days_in_month, _) =
+        (current_month, current_month)
-            get_month_information(current_year, current_month, current_year);
+    };
 
-        add_month_to_table(
+    let add_months_of_year_to_table_result = add_months_of_year_to_table(
-            &mut calendar_vec_deque,
+        &args,
-            &tag,
+        &mut calendar_vec_deque,
-            current_year,
+        &tag,
-            current_month,
+        selected_year,
-            Some(current_day),
+        month_range,
-            day_start_offset,
+        current_month,
-            number_of_days_in_month as usize,
+        current_day_option,
-            &args,
+    );
-        );
+
+    match add_months_of_year_to_table_result {
+        Ok(()) => Ok(futures::stream::iter(calendar_vec_deque).to_output_stream()),
+        Err(error) => Err(error),
+    }
+}
+
+fn get_invalid_year_shell_error(year_tag: &Tag) -> ShellError {
+    ShellError::labeled_error("The year is invalid", "invalid year", year_tag)
+}
+
+struct MonthHelper {
+    day_number_month_starts_on: u32,
+    number_of_days_in_month: u32,
+    selected_year: i32,
+    selected_month: u32,
+}
+
+impl MonthHelper {
+    pub fn new(selected_year: i32, selected_month: u32) -> Result<MonthHelper, ()> {
+        let mut month_helper = MonthHelper {
+            day_number_month_starts_on: 0,
+            number_of_days_in_month: 0,
+            selected_year,
+            selected_month,
+        };
+
+        let chosen_date_result_one = month_helper.update_day_number_month_starts_on();
+        let chosen_date_result_two = month_helper.update_number_of_days_in_month();
+
+        if chosen_date_result_one.is_ok() && chosen_date_result_two.is_ok() {
+            return Ok(month_helper);
+        }
+
+        Err(())
     }
 
-    Ok(futures::stream::iter(calendar_vec_deque).to_output_stream())
+    pub fn get_month_name(&self) -> String {
+        let month_name = match self.selected_month {
+            1 => "january",
+            2 => "february",
+            3 => "march",
+            4 => "april",
+            5 => "may",
+            6 => "june",
+            7 => "july",
+            8 => "august",
+            9 => "september",
+            10 => "october",
+            11 => "november",
+            _ => "december",
+        };
+
+        month_name.to_string()
+    }
+
+    fn update_day_number_month_starts_on(&mut self) -> Result<(), ()> {
+        let naive_date_result =
+            MonthHelper::get_naive_date(self.selected_year, self.selected_month);
+
+        match naive_date_result {
+            Ok(naive_date) => {
+                self.day_number_month_starts_on = naive_date.weekday().num_days_from_sunday();
+                Ok(())
+            }
+            _ => Err(()),
+        }
+    }
+
+    fn update_number_of_days_in_month(&mut self) -> Result<(), ()> {
+        // Chrono does not provide a method to output the amount of days in a month
+        // This is a workaround taken from the example code from the Chrono docs here:
+        // https://docs.rs/chrono/0.3.0/chrono/naive/date/struct.NaiveDate.html#example-30
+        let (adjusted_year, adjusted_month) = if self.selected_month == 12 {
+            (self.selected_year + 1, 1)
+        } else {
+            (self.selected_year, self.selected_month + 1)
+        };
+
+        let naive_date_result = MonthHelper::get_naive_date(adjusted_year, adjusted_month);
+
+        match naive_date_result {
+            Ok(naive_date) => {
+                self.number_of_days_in_month = naive_date.pred().day();
+                Ok(())
+            }
+            _ => Err(()),
+        }
+    }
+
+    fn get_naive_date(selected_year: i32, selected_month: u32) -> Result<NaiveDate, ()> {
+        if let Some(naive_date) = NaiveDate::from_ymd_opt(selected_year, selected_month, 1) {
+            return Ok(naive_date);
+        }
+
+        Err(())
+    }
 }
 
 fn get_current_date() -> (i32, u32, u32) {
-    let local_now: DateTime<Local> = Local::now();
+    let local_now_date = Local::now().date();
 
-    let current_year: i32 = local_now.date().year();
+    let current_year: i32 = local_now_date.year();
-    let current_month: u32 = local_now.date().month();
+    let current_month: u32 = local_now_date.month();
-    let current_day: u32 = local_now.date().day();
+    let current_day: u32 = local_now_date.day();
 
     (current_year, current_month, current_day)
 }
 
-fn add_year_to_table(
+fn add_months_of_year_to_table(
+    args: &EvaluatedWholeStreamCommandArgs,
     mut calendar_vec_deque: &mut VecDeque<Value>,
     tag: &Tag,
-    mut selected_year: i32,
+    selected_year: i32,
-    current_year: i32,
+    (start_month, end_month): (u32, u32),
     current_month: u32,
     current_day_option: Option<u32>,
-    args: &EvaluatedWholeStreamCommandArgs,
+) -> Result<(), ShellError> {
-) {
+    for month_number in start_month..=end_month {
-    for month_number in 1..=12 {
-        let (day_start_offset, number_of_days_in_month, chosen_date_is_valid) =
-            get_month_information(selected_year, month_number, current_year);
-
-        if !chosen_date_is_valid {
-            selected_year = current_year;
-        }
-
         let mut new_current_day_option: Option<u32> = None;
 
         if let Some(current_day) = current_day_option {
@@ -142,39 +227,56 @@ fn add_year_to_table(
             }
         }
 
-        add_month_to_table(
+        let add_month_to_table_result = add_month_to_table(
+            &args,
             &mut calendar_vec_deque,
             &tag,
             selected_year,
             month_number,
             new_current_day_option,
-            day_start_offset,
-            number_of_days_in_month,
-            &args,
         );
+
+        add_month_to_table_result?
     }
+
+    Ok(())
 }
 
-#[allow(clippy::too_many_arguments)]
 fn add_month_to_table(
+    args: &EvaluatedWholeStreamCommandArgs,
     calendar_vec_deque: &mut VecDeque<Value>,
     tag: &Tag,
-    year: i32,
+    selected_year: i32,
-    month: u32,
+    current_month: u32,
-    _current_day_option: Option<u32>, // Can be used in the future to display current day
+    current_day_option: Option<u32>,
-    day_start_offset: usize,
+) -> Result<(), ShellError> {
-    number_of_days_in_month: usize,
+    let month_helper_result = MonthHelper::new(selected_year, current_month);
-    args: &EvaluatedWholeStreamCommandArgs,
+
-) {
+    let month_helper = match month_helper_result {
-    let day_limit = number_of_days_in_month + day_start_offset;
+        Ok(month_helper) => month_helper,
-    let mut day_count: usize = 1;
+        Err(()) => match args.get("full-year") {
+            Some(full_year_value) => {
+                return Err(get_invalid_year_shell_error(&full_year_value.tag()))
+            }
+            None => {
+                return Err(ShellError::labeled_error(
+                    "Issue parsing command",
+                    "invalid command",
+                    tag,
+                ))
+            }
+        },
+    };
+
+    let day_limit = month_helper.number_of_days_in_month + month_helper.day_number_month_starts_on;
+    let mut day_count: u32 = 1;
 
     let days_of_the_week = [
         "sunday",
         "monday",
         "tuesday",
         "wednesday",
-        "thurday",
+        "thursday",
         "friday",
         "saturday",
     ];
@@ -188,32 +290,47 @@ fn add_month_to_table(
         let mut indexmap = IndexMap::new();
 
         if should_show_year_column {
-            indexmap.insert("year".to_string(), UntaggedValue::int(year).into_value(tag));
+            indexmap.insert(
+                "year".to_string(),
+                UntaggedValue::int(month_helper.selected_year).into_value(tag),
+            );
         }
 
         if should_show_quarter_column {
             indexmap.insert(
                 "quarter".to_string(),
-                UntaggedValue::int(get_quarter_number(month)).into_value(tag),
+                UntaggedValue::int(((month_helper.selected_month - 1) / 3) + 1).into_value(tag),
             );
         }
 
         if should_show_month_column {
             let month_value = if should_show_month_names {
-                UntaggedValue::string(get_month_name(month)).into_value(tag)
+                UntaggedValue::string(month_helper.get_month_name()).into_value(tag)
             } else {
-                UntaggedValue::int(month).into_value(tag)
+                UntaggedValue::int(month_helper.selected_month).into_value(tag)
             };
 
             indexmap.insert("month".to_string(), month_value);
         }
 
         for day in &days_of_the_week {
-            let value = if (day_count <= day_limit) && (day_count > day_start_offset) {
+            let should_add_day_number_to_table =
-                UntaggedValue::int(day_count - day_start_offset).into_value(tag)
+                (day_count <= day_limit) && (day_count > month_helper.day_number_month_starts_on);
-            } else {
+
-                UntaggedValue::nothing().into_value(tag)
+            let mut value = UntaggedValue::nothing().into_value(tag);
-            };
+
+            if should_add_day_number_to_table {
+                let day_count_with_offset = day_count - month_helper.day_number_month_starts_on;
+
+                value = UntaggedValue::int(day_count_with_offset).into_value(tag);
+
+                if let Some(current_day) = current_day_option {
+                    if current_day == day_count_with_offset {
+                        // TODO: Update the value here with a color when color support is added
+                        // This colors the current day
+                    }
+                }
+            }
 
             indexmap.insert((*day).to_string(), value);
 
@@ -223,78 +340,18 @@ fn add_month_to_table(
         calendar_vec_deque
             .push_back(UntaggedValue::Row(Dictionary::from(indexmap)).into_value(tag));
     }
+
+    Ok(())
 }
 
-fn get_quarter_number(month_number: u32) -> u8 {
+#[cfg(test)]
-    match month_number {
+mod tests {
-        1..=3 => 1,
+    use super::Cal;
-        4..=6 => 2,
+
-        7..=9 => 3,
+    #[test]
-        _ => 4,
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Cal {})
     }
 }
-
-fn get_month_name(month_number: u32) -> String {
-    let month_name = match month_number {
-        1 => "january",
-        2 => "february",
-        3 => "march",
-        4 => "april",
-        5 => "may",
-        6 => "june",
-        7 => "july",
-        8 => "august",
-        9 => "september",
-        10 => "october",
-        11 => "november",
-        _ => "december",
-    };
-
-    month_name.to_string()
-}
-
-fn get_month_information(
-    selected_year: i32,
-    month: u32,
-    current_year: i32,
-) -> (usize, usize, bool) {
-    let (naive_date, chosen_date_is_valid_one) =
-        get_safe_naive_date(selected_year, month, current_year);
-    let weekday = naive_date.weekday();
-    let (days_in_month, chosen_date_is_valid_two) =
-        get_days_in_month(selected_year, month, current_year);
-
-    (
-        weekday.num_days_from_sunday() as usize,
-        days_in_month,
-        chosen_date_is_valid_one && chosen_date_is_valid_two,
-    )
-}
-
-fn get_days_in_month(selected_year: i32, month: u32, current_year: i32) -> (usize, bool) {
-    // Chrono does not provide a method to output the amount of days in a month
-    // This is a workaround taken from the example code from the Chrono docs here:
-    // https://docs.rs/chrono/0.3.0/chrono/naive/date/struct.NaiveDate.html#example-30
-    let (adjusted_year, adjusted_month) = if month == 12 {
-        (selected_year + 1, 1)
-    } else {
-        (selected_year, month + 1)
-    };
-
-    let (naive_date, chosen_date_is_valid) =
-        get_safe_naive_date(adjusted_year, adjusted_month, current_year);
-
-    (naive_date.pred().day() as usize, chosen_date_is_valid)
-}
-
-fn get_safe_naive_date(
-    selected_year: i32,
-    selected_month: u32,
-    current_year: i32,
-) -> (NaiveDate, bool) {
-    if let Some(naive_date) = NaiveDate::from_ymd_opt(selected_year, selected_month, 1) {
-        return (naive_date, true);
-    }
-
-    (NaiveDate::from_ymd(current_year, selected_month, 1), false)
-}

crates/nu-cli/src/commands/calc.rs

@@ -5,9 +5,7 @@ use nu_protocol::{Primitive, ReturnSuccess, UntaggedValue, Value};
 
 pub struct Calc;
 
-#[derive(Deserialize)]
+#[async_trait]
-pub struct CalcArgs {}
-
 impl WholeStreamCommand for Calc {
     fn name(&self) -> &str {
         "calc"
@@ -17,26 +15,30 @@ impl WholeStreamCommand for Calc {
         "Parse a math expression into a number"
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, calc)?.run()
+        calc(args, registry).await
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[Example {
+        vec![Example {
             description: "Calculate math in the pipeline",
             example: "echo '10 / 4' | calc",
+            result: Some(vec![UntaggedValue::decimal(2.5).into()]),
         }]
     }
 }
 
-pub fn calc(
+pub async fn calc(
-    _: CalcArgs,
+    args: CommandArgs,
-    RunnableContext { input, name, .. }: RunnableContext,
+    _registry: &CommandRegistry,
 ) -> Result<OutputStream, ShellError> {
+    let input = args.input;
+    let name = args.call_info.name_tag.span;
+
     Ok(input
         .map(move |input| {
             if let Ok(string) = input.as_string() {
@@ -52,7 +54,7 @@ pub fn calc(
                 Err(ShellError::labeled_error(
                     "Expected a string from pipeline",
                     "requires string input",
-                    name.clone(),
+                    name,
                 ))
             }
         })
@@ -72,3 +74,15 @@ pub fn parse(math_expression: &str, tag: impl Into<Tag>) -> Result<Value, String
         Err(error) => Err(error.to_string()),
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::Calc;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Calc {})
+    }
+}

crates/nu-cli/src/commands/cd.rs

@@ -14,6 +14,7 @@ pub struct CdArgs {
 
 pub struct Cd;
 
+#[async_trait]
 impl WholeStreamCommand for Cd {
     fn name(&self) -> &str {
         "cd"
@@ -31,36 +32,51 @@ impl WholeStreamCommand for Cd {
         "Change to a new path."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, cd)?.run()
+        let name = args.call_info.name_tag.clone();
+        let shell_manager = args.shell_manager.clone();
+        let (args, _): (CdArgs, _) = args.process(&registry).await?;
+        shell_manager.cd(args, name)
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[
+        vec![
             Example {
                 description: "Change to a new directory called 'dirname'",
                 example: "cd dirname",
+                result: None,
             },
             Example {
                 description: "Change to your home directory",
                 example: "cd",
+                result: None,
             },
             Example {
                 description: "Change to your home directory (alternate version)",
                 example: "cd ~",
+                result: None,
             },
             Example {
                 description: "Change to the previous directory",
                 example: "cd -",
+                result: None,
             },
         ]
     }
 }
 
-fn cd(args: CdArgs, context: RunnableContext) -> Result<OutputStream, ShellError> {
+#[cfg(test)]
-    context.shell_manager.cd(args, &context)
+mod tests {
+    use super::Cd;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Cd {})
+    }
 }

crates/nu-cli/src/commands/classified/block.rs

@@ -6,14 +6,16 @@ use crate::stream::InputStream;
 use futures::stream::TryStreamExt;
 use nu_errors::ShellError;
 use nu_protocol::hir::{Block, ClassifiedCommand, Commands};
-use nu_protocol::{ReturnSuccess, Scope, UntaggedValue, Value};
+use nu_protocol::{ReturnSuccess, UntaggedValue, Value};
 use std::sync::atomic::Ordering;
 
 pub(crate) async fn run_block(
     block: &Block,
     ctx: &mut Context,
     mut input: InputStream,
-    scope: &Scope,
+    it: &Value,
+    vars: &IndexMap<String, Value>,
+    env: &IndexMap<String, String>,
 ) -> Result<InputStream, ShellError> {
     let mut output: Result<InputStream, ShellError> = Ok(InputStream::empty());
     for pipeline in &block.block {
@@ -52,7 +54,7 @@ pub(crate) async fn run_block(
                 return Err(e);
             }
         }
-        output = run_pipeline(pipeline, ctx, input, scope).await;
+        output = run_pipeline(pipeline, ctx, input, it, vars, env).await;
 
         input = InputStream::empty();
     }
@@ -64,10 +66,11 @@ async fn run_pipeline(
     commands: &Commands,
     ctx: &mut Context,
     mut input: InputStream,
-    scope: &Scope,
+    it: &Value,
+    vars: &IndexMap<String, Value>,
+    env: &IndexMap<String, String>,
 ) -> Result<InputStream, ShellError> {
     let mut iter = commands.list.clone().into_iter().peekable();
-
     loop {
         let item: Option<ClassifiedCommand> = iter.next();
         let next: Option<&ClassifiedCommand> = iter.peek();
@@ -78,13 +81,13 @@ async fn run_pipeline(
             }
 
             (Some(ClassifiedCommand::Expr(expr)), _) => {
-                run_expression_block(*expr, ctx, input, scope)?
+                run_expression_block(*expr, ctx, it, vars, env).await?
             }
             (Some(ClassifiedCommand::Error(err)), _) => return Err(err.into()),
             (_, Some(ClassifiedCommand::Error(err))) => return Err(err.clone().into()),
 
             (Some(ClassifiedCommand::Internal(left)), _) => {
-                run_internal_command(left, ctx, input, scope)?
+                run_internal_command(left, ctx, input, it, vars, env).await?
             }
 
             (None, _) => break,

crates/nu-cli/src/commands/classified/expr.rs

@@ -6,22 +6,22 @@ use log::{log_enabled, trace};
 use futures::stream::once;
 use nu_errors::ShellError;
 use nu_protocol::hir::SpannedExpression;
-use nu_protocol::Scope;
+use nu_protocol::Value;
 
-pub(crate) fn run_expression_block(
+pub(crate) async fn run_expression_block(
     expr: SpannedExpression,
     context: &mut Context,
-    _input: InputStream,
+    it: &Value,
-    scope: &Scope,
+    vars: &IndexMap<String, Value>,
+    env: &IndexMap<String, String>,
 ) -> Result<InputStream, ShellError> {
     if log_enabled!(log::Level::Trace) {
         trace!(target: "nu::run::expr", "->");
         trace!(target: "nu::run::expr", "{:?}", expr);
     }
 
-    let scope = scope.clone();
     let registry = context.registry().clone();
-    let output = evaluate_baseline_expr(&expr, &registry, &scope)?;
+    let output = evaluate_baseline_expr(&expr, &registry, it, vars, env).await?;
 
     Ok(once(async { Ok(output) }).to_input_stream())
 }

crates/nu-cli/src/commands/classified/external.rs

@@ -99,10 +99,10 @@ pub(crate) async fn run_external_command(
         ));
     }
 
-    run_with_stdin(command, context, input, scope, is_last)
+    run_with_stdin(command, context, input, scope, is_last).await
 }
 
-fn run_with_stdin(
+async fn run_with_stdin(
     command: ExternalCommand,
     context: &mut Context,
     input: InputStream,
@@ -115,7 +115,9 @@ fn run_with_stdin(
 
     let mut command_args = vec![];
     for arg in command.args.iter() {
-        let value = evaluate_baseline_expr(arg, &context.registry, scope)?;
+        let value =
+            evaluate_baseline_expr(arg, &context.registry, &scope.it, &scope.vars, &scope.env)
+                .await?;
         // Skip any arguments that don't really exist, treating them as optional
         // FIXME: we may want to preserve the gap in the future, though it's hard to say
         // what value we would put in its place.
@@ -509,7 +511,7 @@ mod tests {
         let mut ctx = Context::basic().expect("There was a problem creating a basic context.");
 
         assert!(
-            run_external_command(cmd, &mut ctx, input, &Scope::empty(), false)
+            run_external_command(cmd, &mut ctx, input, &Scope::new(), false)
                 .await
                 .is_err()
         );

crates/nu-cli/src/commands/classified/internal.rs

@@ -7,33 +7,41 @@ use nu_errors::ShellError;
 use nu_protocol::hir::InternalCommand;
 use nu_protocol::{CommandAction, Primitive, ReturnSuccess, Scope, UntaggedValue, Value};
 
-pub(crate) fn run_internal_command(
+pub(crate) async fn run_internal_command(
     command: InternalCommand,
     context: &mut Context,
     input: InputStream,
-    scope: &Scope,
+    it: &Value,
+    vars: &IndexMap<String, Value>,
+    env: &IndexMap<String, String>,
 ) -> Result<InputStream, ShellError> {
     if log_enabled!(log::Level::Trace) {
         trace!(target: "nu::run::internal", "->");
         trace!(target: "nu::run::internal", "{}", command.name);
     }
 
+    let scope = Scope {
+        it: it.clone(),
+        vars: vars.clone(),
+        env: env.clone(),
+    };
     let objects: InputStream = trace_stream!(target: "nu::trace_stream::internal", "input" = input);
     let internal_command = context.expect_command(&command.name);
 
-    let result = {
+    let mut result = {
-        context.run_command(
+        context
-            internal_command?,
+            .run_command(
-            Tag::unknown_anchor(command.name_span),
+                internal_command?,
-            command.args.clone(),
+                Tag::unknown_anchor(command.name_span),
-            scope,
+                command.args.clone(),
-            objects,
+                &scope,
-        )
+                objects,
+            )
+            .await
     };
 
-    let mut result = trace_out_stream!(target: "nu::trace_stream::internal", "output" = result);
     let mut context = context.clone();
-    let scope = scope.clone();
+    // let scope = scope.clone();
 
     let stream = async_stream! {
         let mut soft_errs: Vec<ShellError> = vec![];
@@ -58,6 +66,7 @@ pub(crate) fn run_internal_command(
                             let new_args = RawCommandArgs {
                                 host: context.host.clone(),
                                 ctrl_c: context.ctrl_c.clone(),
+                                current_errors: context.current_errors.clone(),
                                 shell_manager: context.shell_manager.clone(),
                                 call_info: UnevaluatedCallInfo {
                                     args: nu_protocol::hir::Call {
@@ -71,7 +80,7 @@ pub(crate) fn run_internal_command(
                                     scope: scope.clone(),
                                 }
                             };
-                            let mut result = converter.run(new_args.with_input(vec![tagged_contents]), &context.registry);
+                            let mut result = converter.run(new_args.with_input(vec![tagged_contents]), &context.registry).await;
                             let result_vec: Vec<Result<ReturnSuccess, ShellError>> = result.drain_vec().await;
                             for res in result_vec {
                                 match res {

crates/nu-cli/src/commands/clear.rs

@@ -6,41 +6,52 @@ use std::process::Command;
 
 pub struct Clear;
 
+#[async_trait]
 impl WholeStreamCommand for Clear {
     fn name(&self) -> &str {
         "clear"
     }
+
     fn signature(&self) -> Signature {
         Signature::build("clear")
     }
+
     fn usage(&self) -> &str {
         "clears the terminal"
     }
-    fn run(
+
-        &self,
+    async fn run(&self, _: CommandArgs, _: &CommandRegistry) -> Result<OutputStream, ShellError> {
-        args: CommandArgs,
+        if cfg!(windows) {
-        registry: &CommandRegistry,
+            Command::new("cmd")
-    ) -> Result<OutputStream, ShellError> {
+                .args(&["/C", "cls"])
-        clear(args, registry)
+                .status()
+                .expect("failed to execute process");
+        } else if cfg!(unix) {
+            Command::new("/bin/sh")
+                .args(&["-c", "clear"])
+                .status()
+                .expect("failed to execute process");
+        }
+        Ok(OutputStream::empty())
     }
-    fn examples(&self) -> &[Example] {
+
-        &[Example {
+    fn examples(&self) -> Vec<Example> {
+        vec![Example {
             description: "Clear the screen",
             example: "clear",
+            result: None,
         }]
     }
 }
-fn clear(_args: CommandArgs, _registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
+
-    if cfg!(windows) {
+#[cfg(test)]
-        Command::new("cmd")
+mod tests {
-            .args(&["/C", "cls"])
+    use super::Clear;
-            .status()
+
-            .expect("failed to execute process");
+    #[test]
-    } else if cfg!(unix) {
+    fn examples_work_as_expected() {
-        Command::new("/bin/sh")
+        use crate::examples::test as test_examples;
-            .args(&["-c", "clear"])
+
-            .status()
+        test_examples(Clear {})
-            .expect("failed to execute process");
     }
-    Ok(OutputStream::empty())
 }

crates/nu-cli/src/commands/clip.rs

@@ -1,113 +1,109 @@
-#[cfg(feature = "clipboard")]
+use crate::commands::WholeStreamCommand;
-pub mod clipboard {
+use crate::context::CommandRegistry;
-    use crate::commands::WholeStreamCommand;
+use crate::prelude::*;
-    use crate::context::CommandRegistry;
+use futures::stream::StreamExt;
-    use crate::prelude::*;
+use nu_errors::ShellError;
-    use futures::stream::StreamExt;
+use nu_protocol::{Signature, Value};
-    use nu_errors::ShellError;
-    use nu_protocol::{ReturnValue, Signature, Value};
 
-    use clipboard::{ClipboardContext, ClipboardProvider};
+use clipboard::{ClipboardContext, ClipboardProvider};
 
-    pub struct Clip;
+pub struct Clip;
 
-    #[derive(Deserialize)]
+#[async_trait]
-    pub struct ClipArgs {}
+impl WholeStreamCommand for Clip {
-
+    fn name(&self) -> &str {
-    impl WholeStreamCommand for Clip {
+        "clip"
-        fn name(&self) -> &str {
-            "clip"
-        }
-
-        fn signature(&self) -> Signature {
-            Signature::build("clip")
-        }
-
-        fn usage(&self) -> &str {
-            "Copy the contents of the pipeline to the copy/paste buffer"
-        }
-
-        fn run(
-            &self,
-            args: CommandArgs,
-            registry: &CommandRegistry,
-        ) -> Result<OutputStream, ShellError> {
-            args.process(registry, clip)?.run()
-        }
-
-        fn examples(&self) -> &[Example] {
-            &[Example {
-                description: "Save text to the clipboard",
-                example: "echo 'secret value' | clip",
-            }]
-        }
     }
 
-    pub fn clip(
+    fn signature(&self) -> Signature {
-        ClipArgs {}: ClipArgs,
+        Signature::build("clip")
-        RunnableContext { input, name, .. }: RunnableContext,
+    }
+
+    fn usage(&self) -> &str {
+        "Copy the contents of the pipeline to the copy/paste buffer"
+    }
+
+    async fn run(
+        &self,
+        args: CommandArgs,
+        registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        let stream = async_stream! {
+        clip(args, registry).await
-            let values: Vec<Value> = input.collect().await;
-
-            let mut clip_stream = inner_clip(values, name).await;
-            while let Some(value) = clip_stream.next().await {
-                yield value;
-            }
-        };
-
-        let stream: BoxStream<'static, ReturnValue> = stream.boxed();
-
-        Ok(OutputStream::from(stream))
     }
 
-    async fn inner_clip(input: Vec<Value>, name: Tag) -> OutputStream {
+    fn examples(&self) -> Vec<Example> {
-        if let Ok(clip_context) = ClipboardProvider::new() {
+        vec![Example {
-            let mut clip_context: ClipboardContext = clip_context;
+            description: "Save text to the clipboard",
-            let mut new_copy_data = String::new();
+            example: "echo 'secret value' | clip",
-
+            result: None,
-            if !input.is_empty() {
+        }]
-                let mut first = true;
+    }
-                for i in input.iter() {
+}
-                    if !first {
+
-                        new_copy_data.push_str("\n");
+pub async fn clip(
-                    } else {
+    args: CommandArgs,
-                        first = false;
+    _registry: &CommandRegistry,
-                    }
+) -> Result<OutputStream, ShellError> {
-
+    let input = args.input;
-                    let string: String = match i.as_string() {
+    let name = args.call_info.name_tag.clone();
-                        Ok(string) => string.to_string(),
+    let values: Vec<Value> = input.collect().await;
-                        Err(_) => {
+
-                            return OutputStream::one(Err(ShellError::labeled_error(
+    if let Ok(clip_context) = ClipboardProvider::new() {
-                                "Given non-string data",
+        let mut clip_context: ClipboardContext = clip_context;
-                                "expected strings from pipeline",
+        let mut new_copy_data = String::new();
-                                name,
+
-                            )))
+        if !values.is_empty() {
-                        }
+            let mut first = true;
-                    };
+            for i in values.iter() {
-
+                if !first {
-                    new_copy_data.push_str(&string);
+                    new_copy_data.push_str("\n");
-                }
+                } else {
-            }
+                    first = false;
-
+                }
-            match clip_context.set_contents(new_copy_data) {
+
-                Ok(_) => {}
+                let string: String = match i.as_string() {
-                Err(_) => {
+                    Ok(string) => string.to_string(),
-                    return OutputStream::one(Err(ShellError::labeled_error(
+                    Err(_) => {
-                        "Could not set contents of clipboard",
+                        return Err(ShellError::labeled_error(
-                        "could not set contents of clipboard",
+                            "Given non-string data",
-                        name,
+                            "expected strings from pipeline",
-                    )));
+                            name,
-                }
+                        ))
-            }
+                    }
-
+                };
-            OutputStream::empty()
+
-        } else {
+                new_copy_data.push_str(&string);
-            OutputStream::one(Err(ShellError::labeled_error(
+            }
-                "Could not open clipboard",
+        }
-                "could not open clipboard",
+
-                name,
+        match clip_context.set_contents(new_copy_data) {
-            )))
+            Ok(_) => {}
-        }
+            Err(_) => {
+                return Err(ShellError::labeled_error(
+                    "Could not set contents of clipboard",
+                    "could not set contents of clipboard",
+                    name,
+                ));
+            }
+        }
+    } else {
+        return Err(ShellError::labeled_error(
+            "Could not open clipboard",
+            "could not open clipboard",
+            name,
+        ));
+    }
+    Ok(OutputStream::empty())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Clip;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Clip {})
     }
 }

crates/nu-cli/src/commands/command.rs

@@ -7,7 +7,8 @@ use derive_new::new;
 use getset::Getters;
 use nu_errors::ShellError;
 use nu_protocol::hir;
-use nu_protocol::{CallInfo, EvaluatedArgs, ReturnValue, Scope, Signature, Value};
+use nu_protocol::{CallInfo, EvaluatedArgs, ReturnSuccess, Scope, Signature, UntaggedValue, Value};
+use parking_lot::Mutex;
 use serde::{Deserialize, Serialize};
 use std::ops::Deref;
 use std::sync::atomic::AtomicBool;
@@ -20,8 +21,8 @@ pub struct UnevaluatedCallInfo {
 }
 
 impl UnevaluatedCallInfo {
-    pub fn evaluate(self, registry: &CommandRegistry) -> Result<CallInfo, ShellError> {
+    pub async fn evaluate(self, registry: &CommandRegistry) -> Result<CallInfo, ShellError> {
-        let args = evaluate_args(&self.args, registry, &self.scope)?;
+        let args = evaluate_args(&self.args, registry, &self.scope).await?;
 
         Ok(CallInfo {
             args,
@@ -29,14 +30,14 @@ impl UnevaluatedCallInfo {
         })
     }
 
-    pub fn evaluate_with_new_it(
+    pub async fn evaluate_with_new_it(
         self,
         registry: &CommandRegistry,
         it: &Value,
     ) -> Result<CallInfo, ShellError> {
         let mut scope = self.scope.clone();
-        scope = scope.set_it(it.clone());
+        scope.it = it.clone();
-        let args = evaluate_args(&self.args, registry, &scope)?;
+        let args = evaluate_args(&self.args, registry, &scope).await?;
 
         Ok(CallInfo {
             args,
@@ -54,9 +55,11 @@ impl UnevaluatedCallInfo {
 pub struct CommandArgs {
     pub host: Arc<parking_lot::Mutex<Box<dyn Host>>>,
     pub ctrl_c: Arc<AtomicBool>,
+    pub current_errors: Arc<Mutex<Vec<ShellError>>>,
     pub shell_manager: ShellManager,
     pub call_info: UnevaluatedCallInfo,
     pub input: InputStream,
+    pub raw_input: String,
 }
 
 #[derive(Getters, Clone)]
@@ -64,6 +67,7 @@ pub struct CommandArgs {
 pub struct RawCommandArgs {
     pub host: Arc<parking_lot::Mutex<Box<dyn Host>>>,
     pub ctrl_c: Arc<AtomicBool>,
+    pub current_errors: Arc<Mutex<Vec<ShellError>>>,
     pub shell_manager: ShellManager,
     pub call_info: UnevaluatedCallInfo,
 }
@@ -73,9 +77,11 @@ impl RawCommandArgs {
         CommandArgs {
             host: self.host,
             ctrl_c: self.ctrl_c,
+            current_errors: self.current_errors,
             shell_manager: self.shell_manager,
             call_info: self.call_info,
             input: input.into(),
+            raw_input: String::default(),
         }
     }
 }
@@ -87,7 +93,7 @@ impl std::fmt::Debug for CommandArgs {
 }
 
 impl CommandArgs {
-    pub fn evaluate_once(
+    pub async fn evaluate_once(
         self,
         registry: &CommandRegistry,
     ) -> Result<EvaluatedWholeStreamCommandArgs, ShellError> {
@@ -95,7 +101,7 @@ impl CommandArgs {
         let ctrl_c = self.ctrl_c.clone();
         let shell_manager = self.shell_manager.clone();
         let input = self.input;
-        let call_info = self.call_info.evaluate(registry)?;
+        let call_info = self.call_info.evaluate(registry).await?;
 
         Ok(EvaluatedWholeStreamCommandArgs::new(
             host,
@@ -106,7 +112,7 @@ impl CommandArgs {
         ))
     }
 
-    pub fn evaluate_once_with_scope(
+    pub async fn evaluate_once_with_scope(
         self,
         registry: &CommandRegistry,
         scope: &Scope,
@@ -120,7 +126,7 @@ impl CommandArgs {
             args: self.call_info.args,
             scope: scope.clone(),
         };
-        let call_info = call_info.evaluate(registry)?;
+        let call_info = call_info.evaluate(registry).await?;
 
         Ok(EvaluatedWholeStreamCommandArgs::new(
             host,
@@ -131,69 +137,16 @@ impl CommandArgs {
         ))
     }
 
-    pub fn process<'de, T: Deserialize<'de>, O: ToOutputStream>(
+    pub async fn process<'de, T: Deserialize<'de>>(
         self,
         registry: &CommandRegistry,
-        callback: fn(T, RunnableContext) -> Result<O, ShellError>,
+    ) -> Result<(T, InputStream), ShellError> {
-    ) -> Result<RunnableArgs<T, O>, ShellError> {
+        let args = self.evaluate_once(registry).await?;
-        let shell_manager = self.shell_manager.clone();
-        let host = self.host.clone();
-        let ctrl_c = self.ctrl_c.clone();
-        let args = self.evaluate_once(registry)?;
-        let call_info = args.call_info.clone();
-        let (input, args) = args.split();
-        let name_tag = args.call_info.name_tag;
-        let mut deserializer = ConfigDeserializer::from_call_info(call_info);
-
-        Ok(RunnableArgs {
-            args: T::deserialize(&mut deserializer)?,
-            context: RunnableContext {
-                input,
-                registry: registry.clone(),
-                shell_manager,
-                name: name_tag,
-                host,
-                ctrl_c,
-            },
-            callback,
-        })
-    }
-
-    pub fn process_raw<'de, T: Deserialize<'de>>(
-        self,
-        registry: &CommandRegistry,
-        callback: fn(T, RunnableContext, RawCommandArgs) -> Result<OutputStream, ShellError>,
-    ) -> Result<RunnableRawArgs<T>, ShellError> {
-        let raw_args = RawCommandArgs {
-            host: self.host.clone(),
-            ctrl_c: self.ctrl_c.clone(),
-            shell_manager: self.shell_manager.clone(),
-            call_info: self.call_info.clone(),
-        };
-
-        let shell_manager = self.shell_manager.clone();
-        let host = self.host.clone();
-        let ctrl_c = self.ctrl_c.clone();
-        let args = self.evaluate_once(registry)?;
         let call_info = args.call_info.clone();
 
-        let (input, args) = args.split();
-        let name_tag = args.call_info.name_tag;
         let mut deserializer = ConfigDeserializer::from_call_info(call_info);
 
-        Ok(RunnableRawArgs {
+        Ok((T::deserialize(&mut deserializer)?, args.input))
-            args: T::deserialize(&mut deserializer)?,
-            context: RunnableContext {
-                input,
-                registry: registry.clone(),
-                shell_manager,
-                name: name_tag,
-                host,
-                ctrl_c,
-            },
-            raw_args,
-            callback,
-        })
     }
 }
 
@@ -202,8 +155,10 @@ pub struct RunnableContext {
     pub shell_manager: ShellManager,
     pub host: Arc<parking_lot::Mutex<Box<dyn Host>>>,
     pub ctrl_c: Arc<AtomicBool>,
+    pub current_errors: Arc<Mutex<Vec<ShellError>>>,
     pub registry: CommandRegistry,
     pub name: Tag,
+    pub raw_input: String,
 }
 
 impl RunnableContext {
@@ -212,34 +167,6 @@ impl RunnableContext {
     }
 }
 
-pub struct RunnableArgs<T, O: ToOutputStream> {
-    args: T,
-    context: RunnableContext,
-    callback: fn(T, RunnableContext) -> Result<O, ShellError>,
-}
-
-impl<T, O: ToOutputStream> RunnableArgs<T, O> {
-    pub fn run(self) -> Result<OutputStream, ShellError> {
-        (self.callback)(self.args, self.context).map(|v| v.to_output_stream())
-    }
-}
-
-pub struct RunnableRawArgs<T> {
-    args: T,
-    raw_args: RawCommandArgs,
-    context: RunnableContext,
-    callback: fn(T, RunnableContext, RawCommandArgs) -> Result<OutputStream, ShellError>,
-}
-
-impl<T> RunnableRawArgs<T> {
-    pub fn run(self) -> OutputStream {
-        match (self.callback)(self.args, self.context, self.raw_args) {
-            Ok(stream) => stream,
-            Err(err) => OutputStream::one(Err(err)),
-        }
-    }
-}
-
 pub struct EvaluatedWholeStreamCommandArgs {
     pub args: EvaluatedCommandArgs,
     pub input: InputStream,
@@ -353,8 +280,10 @@ impl EvaluatedCommandArgs {
 pub struct Example {
     pub example: &'static str,
     pub description: &'static str,
+    pub result: Option<Vec<Value>>,
 }
 
+#[async_trait]
 pub trait WholeStreamCommand: Send + Sync {
     fn name(&self) -> &str;
 
@@ -364,7 +293,7 @@ pub trait WholeStreamCommand: Send + Sync {
 
     fn usage(&self) -> &str;
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
@@ -374,8 +303,8 @@ pub trait WholeStreamCommand: Send + Sync {
         false
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[]
+        Vec::new()
     }
 }
 
@@ -414,11 +343,15 @@ impl Command {
         self.0.usage()
     }
 
-    pub fn run(&self, args: CommandArgs, registry: &CommandRegistry) -> OutputStream {
+    pub async fn run(&self, args: CommandArgs, registry: &CommandRegistry) -> OutputStream {
         if args.call_info.switch_present("help") {
-            get_help(&*self.0, registry).into()
+            let cl = self.0.clone();
+            let registry = registry.clone();
+            OutputStream::one(Ok(ReturnSuccess::Value(
+                UntaggedValue::string(get_help(&*cl, &registry)).into_value(Tag::unknown()),
+            )))
         } else {
-            match self.0.run(args, registry) {
+            match self.0.run(args, registry).await {
                 Ok(stream) => stream,
                 Err(err) => OutputStream::one(Err(err)),
             }
@@ -439,6 +372,7 @@ pub struct FnFilterCommand {
     func: fn(EvaluatedFilterCommandArgs) -> Result<OutputStream, ShellError>,
 }
 
+#[async_trait]
 impl WholeStreamCommand for FnFilterCommand {
     fn name(&self) -> &str {
         &self.name
@@ -448,47 +382,49 @@ impl WholeStreamCommand for FnFilterCommand {
         "usage"
     }
 
-    fn run(
+    async fn run(
         &self,
-        args: CommandArgs,
+        CommandArgs {
-        registry: &CommandRegistry,
-    ) -> Result<OutputStream, ShellError> {
-        let CommandArgs {
             host,
             ctrl_c,
             shell_manager,
             call_info,
-            input,
+            mut input,
-        } = args;
+            ..
-
+        }: CommandArgs,
+        registry: &CommandRegistry,
+    ) -> Result<OutputStream, ShellError> {
         let host: Arc<parking_lot::Mutex<dyn Host>> = host.clone();
         let registry: CommandRegistry = registry.clone();
         let func = self.func;
 
-        let result = input.map(move |it| {
+        let stream = async_stream! {
-            let registry = registry.clone();
+            while let Some(it) = input.next().await {
-            let call_info = match call_info.clone().evaluate_with_new_it(&registry, &it) {
+                let registry = registry.clone();
-                Err(err) => return OutputStream::from(vec![Err(err)]).values,
+                let call_info = match call_info.clone().evaluate_with_new_it(&registry, &it).await {
-                Ok(args) => args,
+                    Err(err) => { yield Err(err); return; },
-            };
+                    Ok(args) => args,
+                };
 
-            let args = EvaluatedFilterCommandArgs::new(
+                let args = EvaluatedFilterCommandArgs::new(
-                host.clone(),
+                    host.clone(),
-                ctrl_c.clone(),
+                    ctrl_c.clone(),
-                shell_manager.clone(),
+                    shell_manager.clone(),
-                call_info,
+                    call_info,
-            );
+                );
 
-            match func(args) {
+                match func(args) {
-                Err(err) => OutputStream::from(vec![Err(err)]).values,
+                    Err(err) => yield Err(err),
-                Ok(stream) => stream.values,
+                    Ok(mut stream) => {
+                        while let Some(value) = stream.values.next().await {
+                            yield value;
+                        }
+                    }
+                }
             }
-        });
+        };
 
-        let result = result.flatten();
+        Ok(stream.to_output_stream())
-        let result: BoxStream<ReturnValue> = result.boxed();
-
-        Ok(result.into())
     }
 }
 

crates/nu-cli/src/commands/compact.rs

@@ -1,9 +1,10 @@
 use crate::commands::WholeStreamCommand;
 use crate::context::CommandRegistry;
 use crate::prelude::*;
+use futures::future;
 use futures::stream::StreamExt;
 use nu_errors::ShellError;
-use nu_protocol::{Signature, SyntaxShape, UntaggedValue, Value};
+use nu_protocol::{ReturnSuccess, Signature, SyntaxShape, UntaggedValue, Value};
 use nu_source::Tagged;
 
 pub struct Compact;
@@ -13,6 +14,7 @@ pub struct CompactArgs {
     rest: Vec<Tagged<String>>,
 }
 
+#[async_trait]
 impl WholeStreamCommand for Compact {
     fn name(&self) -> &str {
         "compact"
@@ -26,43 +28,78 @@ impl WholeStreamCommand for Compact {
         "Creates a table with non-empty rows"
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, compact)?.run()
+        compact(args, registry).await
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[Example {
+        vec![
-            description: "Remove all directory entries, except those with a 'target'",
+            Example {
-            example: "ls -af | compact target",
+                description: "Filter out all null entries in a list",
-        }]
+                example: "echo [1 2 $null 3 $null $null] | compact target",
+                result: Some(vec![
+                    UntaggedValue::int(1).into(),
+                    UntaggedValue::int(2).into(),
+                    UntaggedValue::int(3).into(),
+                ]),
+            },
+            Example {
+                description: "Filter out all directory entries having no 'target'",
+                example: "ls -af | compact target",
+                result: None,
+            },
+        ]
     }
 }
 
-pub fn compact(
+pub async fn compact(
-    CompactArgs { rest: columns }: CompactArgs,
+    args: CommandArgs,
-    RunnableContext { input, .. }: RunnableContext,
+    registry: &CommandRegistry,
 ) -> Result<OutputStream, ShellError> {
-    let objects = input.filter(move |item| {
+    let registry = registry.clone();
-        let keep = if columns.is_empty() {
+    let (CompactArgs { rest: columns }, input) = args.process(&registry).await?;
-            item.is_some()
+    Ok(input
-        } else {
+        .filter_map(move |item| {
-            match item {
+            future::ready(if columns.is_empty() {
-                Value {
+                if !item.is_empty() {
-                    value: UntaggedValue::Row(ref r),
+                    Some(ReturnSuccess::value(item))
-                    ..
+                } else {
-                } => columns
+                    None
-                    .iter()
+                }
-                    .all(|field| r.get_data(field).borrow().is_some()),
+            } else {
-                _ => false,
+                match item {
-            }
+                    Value {
-        };
+                        value: UntaggedValue::Row(ref r),
-
+                        ..
-        futures::future::ready(keep)
+                    } => {
-    });
+                        if columns
-
+                            .iter()
-    Ok(objects.from_input_stream())
+                            .all(|field| r.get_data(field).borrow().is_some())
+                        {
+                            Some(ReturnSuccess::value(item))
+                        } else {
+                            None
+                        }
+                    }
+                    _ => None,
+                }
+            })
+        })
+        .to_output_stream())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Compact;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Compact {})
+    }
 }

crates/nu-cli/src/commands/config.rs

@@ -20,6 +20,7 @@ pub struct ConfigArgs {
     path: Tagged<bool>,
 }
 
+#[async_trait]
 impl WholeStreamCommand for Config {
     fn name(&self) -> &str {
         "config"
@@ -30,7 +31,7 @@ impl WholeStreamCommand for Config {
             .named(
                 "load",
                 SyntaxShape::Path,
-                "load the config from the path give",
+                "load the config from the path given",
                 Some('l'),
             )
             .named(
@@ -65,157 +66,195 @@ impl WholeStreamCommand for Config {
         "Configuration management."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, config)?.run()
+        config(args, registry).await
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[
+        vec![
             Example {
                 description: "See all config values",
                 example: "config",
+                result: None,
             },
             Example {
                 description: "Set completion_mode to circular",
                 example: "config --set [completion_mode circular]",
+                result: None,
             },
             Example {
                 description: "Store the contents of the pipeline as a path",
                 example: "echo ['/usr/bin' '/bin'] | config --set_into path",
+                result: None,
             },
             Example {
                 description: "Get the current startup commands",
                 example: "config --get startup",
+                result: None,
             },
             Example {
                 description: "Remove the startup commands",
                 example: "config --remove startup",
+                result: None,
             },
             Example {
                 description: "Clear the config (be careful!)",
                 example: "config --clear",
+                result: None,
             },
             Example {
                 description: "Get the path to the current config file",
                 example: "config --path",
+                result: None,
             },
         ]
     }
 }
 
-pub fn config(
+pub async fn config(
-    ConfigArgs {
+    args: CommandArgs,
-        load,
+    registry: &CommandRegistry,
-        set,
-        set_into,
-        get,
-        clear,
-        remove,
-        path,
-    }: ConfigArgs,
-    RunnableContext { name, input, .. }: RunnableContext,
 ) -> Result<OutputStream, ShellError> {
-    let name_span = name.clone();
+    let name_span = args.call_info.name_tag.clone();
+    let name = args.call_info.name_tag.clone();
+    let registry = registry.clone();
 
-    let stream = async_stream! {
+    let (
-        let configuration = if let Some(supplied) = load {
+        ConfigArgs {
-            Some(supplied.item().clone())
+            load,
-        } else {
+            set,
-            None
+            set_into,
-        };
+            get,
+            clear,
+            remove,
+            path,
+        },
+        input,
+    ) = args.process(&registry).await?;
 
-        let mut result = crate::data::config::read(name_span, &configuration)?;
+    let configuration = if let Some(supplied) = load {
-
+        Some(supplied.item().clone())
-        if let Some(v) = get {
+    } else {
-            let key = v.to_string();
+        None
-            let value = result
-                .get(&key)
-                .ok_or_else(|| ShellError::labeled_error("Missing key in config", "key", v.tag()))?;
-
-            match value {
-                Value {
-                    value: UntaggedValue::Table(list),
-                    ..
-                } => {
-                    for l in list {
-                        let value = l.clone();
-                        yield ReturnSuccess::value(l.clone());
-                    }
-                }
-                x => yield ReturnSuccess::value(x.clone()),
-            }
-        }
-        else if let Some((key, value)) = set {
-            result.insert(key.to_string(), value.clone());
-
-            config::write(&result, &configuration)?;
-
-            yield ReturnSuccess::value(UntaggedValue::Row(result.into()).into_value(&value.tag));
-        }
-        else if let Some(v) = set_into {
-            let rows: Vec<Value> = input.collect().await;
-            let key = v.to_string();
-
-            if rows.len() == 0 {
-                yield Err(ShellError::labeled_error("No values given for set_into", "needs value(s) from pipeline", v.tag()));
-            } else if rows.len() == 1 {
-                // A single value
-                let value = &rows[0];
-
-                result.insert(key.to_string(), value.clone());
-
-                config::write(&result, &configuration)?;
-
-                yield ReturnSuccess::value(UntaggedValue::Row(result.into()).into_value(name));
-            } else {
-                // Take in the pipeline as a table
-                let value = UntaggedValue::Table(rows).into_value(name.clone());
-
-                result.insert(key.to_string(), value.clone());
-
-                config::write(&result, &configuration)?;
-
-                yield ReturnSuccess::value(UntaggedValue::Row(result.into()).into_value(name));
-            }
-        }
-        else if let Tagged { item: true, tag } = clear {
-            result.clear();
-
-            config::write(&result, &configuration)?;
-
-            yield ReturnSuccess::value(UntaggedValue::Row(result.into()).into_value(tag));
-
-            return;
-        }
-        else if let Tagged { item: true, tag } = path {
-            let path = config::default_path_for(&configuration)?;
-
-            yield ReturnSuccess::value(UntaggedValue::Primitive(Primitive::Path(path)).into_value(tag));
-        }
-        else if let Some(v) = remove {
-            let key = v.to_string();
-
-            if result.contains_key(&key) {
-                result.swap_remove(&key);
-                config::write(&result, &configuration)?
-            } else {
-                yield Err(ShellError::labeled_error(
-                    "Key does not exist in config",
-                    "key",
-                    v.tag(),
-                ));
-            }
-
-            yield ReturnSuccess::value(UntaggedValue::Row(result.into()).into_value(v.tag()));
-        }
-        else {
-            yield ReturnSuccess::value(UntaggedValue::Row(result.into()).into_value(name));
-        }
     };
 
-    Ok(stream.to_output_stream())
+    let mut result = crate::data::config::read(name_span, &configuration)?;
+
+    Ok(if let Some(v) = get {
+        let key = v.to_string();
+        let value = result
+            .get(&key)
+            .ok_or_else(|| ShellError::labeled_error("Missing key in config", "key", v.tag()))?;
+
+        match value {
+            Value {
+                value: UntaggedValue::Table(list),
+                ..
+            } => {
+                let list: Vec<_> = list
+                    .iter()
+                    .map(|x| ReturnSuccess::value(x.clone()))
+                    .collect();
+
+                futures::stream::iter(list).to_output_stream()
+            }
+            x => {
+                let x = x.clone();
+                OutputStream::one(ReturnSuccess::value(x))
+            }
+        }
+    } else if let Some((key, value)) = set {
+        result.insert(key.to_string(), value.clone());
+
+        config::write(&result, &configuration)?;
+
+        OutputStream::one(ReturnSuccess::value(
+            UntaggedValue::Row(result.into()).into_value(&value.tag),
+        ))
+    } else if let Some(v) = set_into {
+        let rows: Vec<Value> = input.collect().await;
+        let key = v.to_string();
+
+        if rows.is_empty() {
+            return Err(ShellError::labeled_error(
+                "No values given for set_into",
+                "needs value(s) from pipeline",
+                v.tag(),
+            ));
+        } else if rows.len() == 1 {
+            // A single value
+            let value = &rows[0];
+
+            result.insert(key, value.clone());
+
+            config::write(&result, &configuration)?;
+
+            OutputStream::one(ReturnSuccess::value(
+                UntaggedValue::Row(result.into()).into_value(name),
+            ))
+        } else {
+            // Take in the pipeline as a table
+            let value = UntaggedValue::Table(rows).into_value(name.clone());
+
+            result.insert(key, value);
+
+            config::write(&result, &configuration)?;
+
+            OutputStream::one(ReturnSuccess::value(
+                UntaggedValue::Row(result.into()).into_value(name),
+            ))
+        }
+    } else if let Tagged { item: true, tag } = clear {
+        result.clear();
+
+        config::write(&result, &configuration)?;
+
+        OutputStream::one(ReturnSuccess::value(
+            UntaggedValue::Row(result.into()).into_value(tag),
+        ))
+    } else if let Tagged { item: true, tag } = path {
+        let path = config::default_path_for(&configuration)?;
+
+        OutputStream::one(ReturnSuccess::value(
+            UntaggedValue::Primitive(Primitive::Path(path)).into_value(tag),
+        ))
+    } else if let Some(v) = remove {
+        let key = v.to_string();
+
+        if result.contains_key(&key) {
+            result.swap_remove(&key);
+            config::write(&result, &configuration)?;
+            futures::stream::iter(vec![ReturnSuccess::value(
+                UntaggedValue::Row(result.into()).into_value(v.tag()),
+            )])
+            .to_output_stream()
+        } else {
+            return Err(ShellError::labeled_error(
+                "Key does not exist in config",
+                "key",
+                v.tag(),
+            ));
+        }
+    } else {
+        futures::stream::iter(vec![ReturnSuccess::value(
+            UntaggedValue::Row(result.into()).into_value(name),
+        )])
+        .to_output_stream()
+    })
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Config;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Config {})
+    }
 }

crates/nu-cli/src/commands/count.rs

@@ -3,13 +3,11 @@ use crate::context::CommandRegistry;
 use crate::prelude::*;
 use futures::stream::StreamExt;
 use nu_errors::ShellError;
-use nu_protocol::{ReturnSuccess, Signature, UntaggedValue, Value};
+use nu_protocol::{Signature, UntaggedValue, Value};
 
 pub struct Count;
 
-#[derive(Deserialize)]
+#[async_trait]
-pub struct CountArgs {}
-
 impl WholeStreamCommand for Count {
     fn name(&self) -> &str {
         "count"
@@ -23,31 +21,36 @@ impl WholeStreamCommand for Count {
         "Show the total number of rows or items."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
-        registry: &CommandRegistry,
+        _registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, count)?.run()
+        let name = args.call_info.name_tag.clone();
+        let rows: Vec<Value> = args.input.collect().await;
+
+        Ok(OutputStream::one(
+            UntaggedValue::int(rows.len()).into_value(name),
+        ))
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[Example {
+        vec![Example {
-            description: "Count the number of files/directories in the current directory",
+            description: "Count the number of entries in a list",
-            example: "ls | count",
+            example: "echo [1 2 3 4 5] | count",
+            result: Some(vec![UntaggedValue::int(5).into()]),
         }]
     }
 }
 
-pub fn count(
+#[cfg(test)]
-    CountArgs {}: CountArgs,
+mod tests {
-    RunnableContext { input, name, .. }: RunnableContext,
+    use super::Count;
-) -> Result<OutputStream, ShellError> {
-    let stream = async_stream! {
-        let rows: Vec<Value> = input.collect().await;
 
-        yield ReturnSuccess::value(UntaggedValue::int(rows.len()).into_value(name))
+    #[test]
-    };
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
 
-    Ok(stream.to_output_stream())
+        test_examples(Count {})
+    }
 }

crates/nu-cli/src/commands/cp.rs

@@ -15,6 +15,7 @@ pub struct CopyArgs {
     pub recursive: Tagged<bool>,
 }
 
+#[async_trait]
 impl WholeStreamCommand for Cpy {
     fn name(&self) -> &str {
         "cp"
@@ -35,29 +36,41 @@ impl WholeStreamCommand for Cpy {
         "Copy files."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, cp)?.run()
+        let shell_manager = args.shell_manager.clone();
+        let name = args.call_info.name_tag.clone();
+        let (args, _) = args.process(&registry).await?;
+        shell_manager.cp(args, name)
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[
+        vec![
             Example {
                 description: "Copy myfile to dir_b",
                 example: "cp myfile dir_b",
+                result: None,
             },
             Example {
                 description: "Recursively copy dir_a to dir_b",
                 example: "cp -r dir_a dir_b",
+                result: None,
             },
         ]
     }
 }
 
-pub fn cp(args: CopyArgs, context: RunnableContext) -> Result<OutputStream, ShellError> {
+#[cfg(test)]
-    let shell_manager = context.shell_manager.clone();
+mod tests {
-    shell_manager.cp(args, &context)
+    use super::Cpy;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Cpy {})
+    }
 }

crates/nu-cli/src/commands/date.rs

@@ -11,6 +11,7 @@ use nu_protocol::{Signature, UntaggedValue};
 
 pub struct Date;
 
+#[async_trait]
 impl WholeStreamCommand for Date {
     fn name(&self) -> &str {
         "date"
@@ -26,23 +27,25 @@ impl WholeStreamCommand for Date {
         "Get the current datetime."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        date(args, registry)
+        date(args, registry).await
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[
+        vec![
             Example {
                 description: "Get the current local time and date",
                 example: "date",
+                result: None,
             },
             Example {
                 description: "Get the current UTC time and date",
                 example: "date --utc",
+                result: None,
             },
         ]
     }
@@ -88,10 +91,13 @@ where
     UntaggedValue::Row(Dictionary::from(indexmap)).into_value(&tag)
 }
 
-pub fn date(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
+pub async fn date(
-    let args = args.evaluate_once(registry)?;
+    args: CommandArgs,
+    registry: &CommandRegistry,
+) -> Result<OutputStream, ShellError> {
+    let registry = registry.clone();
+    let args = args.evaluate_once(&registry).await?;
 
-    let mut date_out = VecDeque::new();
     let tag = args.call_info.name_tag.clone();
 
     let value = if args.has("utc") {
@@ -102,7 +108,17 @@ pub fn date(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStrea
         date_to_value(local, tag)
     };
 
-    date_out.push_back(value);
+    Ok(OutputStream::one(value))
-
+}
-    Ok(futures::stream::iter(date_out).to_output_stream())
+
+#[cfg(test)]
+mod tests {
+    use super::Date;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Date {})
+    }
 }

crates/nu-cli/src/commands/debug.rs

@@ -10,6 +10,7 @@ pub struct DebugArgs {
     raw: bool,
 }
 
+#[async_trait]
 impl WholeStreamCommand for Debug {
     fn name(&self) -> &str {
         "debug"
@@ -23,19 +24,21 @@ impl WholeStreamCommand for Debug {
         "Print the Rust debug representation of the values"
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, debug_value)?.run()
+        debug_value(args, registry).await
     }
 }
 
-fn debug_value(
+async fn debug_value(
-    DebugArgs { raw }: DebugArgs,
+    args: CommandArgs,
-    RunnableContext { input, .. }: RunnableContext,
+    registry: &CommandRegistry,
-) -> Result<impl ToOutputStream, ShellError> {
+) -> Result<OutputStream, ShellError> {
+    let registry = registry.clone();
+    let (DebugArgs { raw }, input) = args.process(&registry).await?;
     Ok(input
         .map(move |v| {
             if raw {
@@ -48,3 +51,15 @@ fn debug_value(
         })
         .to_output_stream())
 }
+
+#[cfg(test)]
+mod tests {
+    use super::Debug;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Debug {})
+    }
+}

crates/nu-cli/src/commands/default.rs

@@ -14,6 +14,7 @@ struct DefaultArgs {
 
 pub struct Default;
 
+#[async_trait]
 impl WholeStreamCommand for Default {
     fn name(&self) -> &str {
         "default"
@@ -33,30 +34,32 @@ impl WholeStreamCommand for Default {
         "Sets a default row's column if missing."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, default)?.run()
+        default(args, registry).await
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[Example {
+        vec![Example {
             description: "Give a default 'target' to all file entries",
             example: "ls -af | default target 'nothing'",
+            result: None,
         }]
     }
 }
 
-fn default(
+async fn default(
-    DefaultArgs { column, value }: DefaultArgs,
+    args: CommandArgs,
-    RunnableContext { input, .. }: RunnableContext,
+    registry: &CommandRegistry,
 ) -> Result<OutputStream, ShellError> {
-    let stream = input
+    let registry = registry.clone();
-        .map(move |item| {
+    let (DefaultArgs { column, value }, input) = args.process(&registry).await?;
-            let mut result = VecDeque::new();
 
+    Ok(input
+        .map(move |item| {
             let should_add = match item {
                 Value {
                     value: UntaggedValue::Row(ref r),
@@ -67,16 +70,24 @@ fn default(
 
             if should_add {
                 match item.insert_data_at_path(&column.item, value.clone()) {
-                    Some(new_value) => result.push_back(ReturnSuccess::value(new_value)),
+                    Some(new_value) => ReturnSuccess::value(new_value),
-                    None => result.push_back(ReturnSuccess::value(item)),
+                    None => ReturnSuccess::value(item),
                 }
             } else {
-                result.push_back(ReturnSuccess::value(item));
+                ReturnSuccess::value(item)
             }
-
-            futures::stream::iter(result)
         })
-        .flatten();
+        .to_output_stream())
-
+}
-    Ok(stream.to_output_stream())
+
+#[cfg(test)]
+mod tests {
+    use super::Default;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Default {})
+    }
 }

crates/nu-cli/src/commands/drop.rs

@@ -2,7 +2,7 @@ use crate::commands::WholeStreamCommand;
 use crate::context::CommandRegistry;
 use crate::prelude::*;
 use nu_errors::ShellError;
-use nu_protocol::{ReturnSuccess, Signature, SyntaxShape, Value};
+use nu_protocol::{Signature, SyntaxShape, UntaggedValue};
 use nu_source::Tagged;
 
 pub struct Drop;
@@ -12,6 +12,7 @@ pub struct DropArgs {
     rows: Option<Tagged<u64>>,
 }
 
+#[async_trait]
 impl WholeStreamCommand for Drop {
     fn name(&self) -> &str {
         "drop"
@@ -29,31 +30,13 @@ impl WholeStreamCommand for Drop {
         "Drop the last number of rows."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, drop)?.run()
+        let (DropArgs { rows }, input) = args.process(&registry).await?;
-    }
+        let mut v: Vec<_> = input.into_vec().await;
-
-    fn examples(&self) -> &[Example] {
-        &[
-            Example {
-                description: "Remove the last item of a list/table",
-                example: "echo [1 2 3] | drop",
-            },
-            Example {
-                description: "Remove the last 2 items of a list/table",
-                example: "echo [1 2 3] | drop 2",
-            },
-        ]
-    }
-}
-
-fn drop(DropArgs { rows }: DropArgs, context: RunnableContext) -> Result<OutputStream, ShellError> {
-    let stream = async_stream! {
-        let v: Vec<_> = context.input.into_vec().await;
 
         let rows_to_drop = if let Some(quantity) = rows {
             *quantity as usize
@@ -61,13 +44,40 @@ fn drop(DropArgs { rows }: DropArgs, context: RunnableContext) -> Result<OutputS
             1
         };
 
-        if rows_to_drop < v.len() {
+        for _ in 0..rows_to_drop {
-            let k = v.len() - rows_to_drop;
+            v.pop();
-            for x in v[0..k].iter() {
-                let y: Value = x.clone();
-                yield ReturnSuccess::value(y)
-            }
         }
-    };
+
-    Ok(stream.to_output_stream())
+        Ok(futures::stream::iter(v).to_output_stream())
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![
+            Example {
+                description: "Remove the last item of a list/table",
+                example: "echo [1 2 3] | drop",
+                result: Some(vec![
+                    UntaggedValue::int(1).into(),
+                    UntaggedValue::int(2).into(),
+                ]),
+            },
+            Example {
+                description: "Remove the last 2 items of a list/table",
+                example: "echo [1 2 3] | drop 2",
+                result: Some(vec![UntaggedValue::int(1).into()]),
+            },
+        ]
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Drop;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Drop {})
+    }
 }

crates/nu-cli/src/commands/du.rs

@@ -7,6 +7,7 @@ use nu_errors::ShellError;
 use nu_protocol::{ReturnSuccess, Signature, SyntaxShape, UntaggedValue, Value};
 use nu_source::Tagged;
 use std::path::PathBuf;
+use std::sync::atomic::Ordering;
 
 const NAME: &str = "du";
 const GLOB_PARAMS: MatchOptions = MatchOptions {
@@ -29,6 +30,7 @@ pub struct DuArgs {
     min_size: Option<Tagged<u64>>,
 }
 
+#[async_trait]
 impl WholeStreamCommand for Du {
     fn name(&self) -> &str {
         NAME
@@ -71,25 +73,30 @@ impl WholeStreamCommand for Du {
         "Find disk usage sizes of specified items"
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, du)?.run()
+        du(args, registry).await
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[Example {
+        vec![Example {
             description: "Disk usage of the current directory",
-            example: "du *",
+            example: "du",
+            result: None,
         }]
     }
 }
 
-fn du(args: DuArgs, ctx: RunnableContext) -> Result<OutputStream, ShellError> {
+async fn du(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
-    let tag = ctx.name.clone();
+    let registry = registry.clone();
+    let tag = args.call_info.name_tag.clone();
+    let ctrl_c = args.ctrl_c.clone();
+    let ctrl_c_copy = ctrl_c.clone();
 
+    let (args, _): (DuArgs, _) = args.process(&registry).await?;
     let exclude = args.exclude.map_or(Ok(None), move |x| {
         Pattern::new(&x.item)
             .map(Option::Some)
@@ -118,7 +125,6 @@ fn du(args: DuArgs, ctx: RunnableContext) -> Result<OutputStream, ShellError> {
     })
     .map(|v| v.map_err(glob_err_into));
 
-    let ctrl_c = ctx.ctrl_c;
     let all = args.all;
     let deref = args.deref;
     let max_depth = args.max_depth.map(|f| f.item);
@@ -132,22 +138,27 @@ fn du(args: DuArgs, ctx: RunnableContext) -> Result<OutputStream, ShellError> {
         all,
     };
 
-    let stream = futures::stream::iter(paths)
+    let inp = futures::stream::iter(paths);
-        .interruptible(ctrl_c)
-        .map(move |path| match path {
-            Ok(p) => {
-                if p.is_dir() {
-                    Ok(ReturnSuccess::Value(
-                        DirInfo::new(p, &params, max_depth).into(),
-                    ))
-                } else {
-                    FileInfo::new(p, deref, tag.clone()).map(|v| ReturnSuccess::Value(v.into()))
-                }
-            }
-            Err(e) => Err(e),
-        });
 
-    Ok(stream.to_output_stream())
+    Ok(inp
+        .flat_map(move |path| match path {
+            Ok(p) => {
+                let mut output = vec![];
+                if p.is_dir() {
+                    output.push(Ok(ReturnSuccess::Value(
+                        DirInfo::new(p, &params, max_depth, ctrl_c.clone()).into(),
+                    )));
+                } else {
+                    for v in FileInfo::new(p, deref, tag.clone()).into_iter() {
+                        output.push(Ok(ReturnSuccess::Value(v.into())));
+                    }
+                }
+                futures::stream::iter(output)
+            }
+            Err(e) => futures::stream::iter(vec![Err(e)]),
+        })
+        .interruptible(ctrl_c_copy)
+        .to_output_stream())
 }
 
 pub struct DirBuilder {
@@ -219,7 +230,12 @@ impl FileInfo {
 }
 
 impl DirInfo {
-    pub fn new(path: impl Into<PathBuf>, params: &DirBuilder, depth: Option<u64>) -> Self {
+    pub fn new(
+        path: impl Into<PathBuf>,
+        params: &DirBuilder,
+        depth: Option<u64>,
+        ctrl_c: Arc<AtomicBool>,
+    ) -> Self {
         let path = path.into();
 
         let mut s = Self {
@@ -235,9 +251,15 @@ impl DirInfo {
         match std::fs::read_dir(&s.path) {
             Ok(d) => {
                 for f in d {
+                    if ctrl_c.load(Ordering::SeqCst) {
+                        break;
+                    }
+
                     match f {
                         Ok(i) => match i.file_type() {
-                            Ok(t) if t.is_dir() => s = s.add_dir(i.path(), depth, &params),
+                            Ok(t) if t.is_dir() => {
+                                s = s.add_dir(i.path(), depth, &params, ctrl_c.clone())
+                            }
                             Ok(_t) => s = s.add_file(i.path(), &params),
                             Err(e) => s = s.add_error(e.into()),
                         },
@@ -255,6 +277,7 @@ impl DirInfo {
         path: impl Into<PathBuf>,
         mut depth: Option<u64>,
         params: &DirBuilder,
+        ctrl_c: Arc<AtomicBool>,
     ) -> Self {
         if let Some(current) = depth {
             if let Some(new) = current.checked_sub(1) {
@@ -264,7 +287,7 @@ impl DirInfo {
             }
         }
 
-        let d = DirInfo::new(path, &params, depth);
+        let d = DirInfo::new(path, &params, depth, ctrl_c);
         self.size += d.size;
         self.blocks += d.blocks;
         self.dirs.push(d);
@@ -397,3 +420,15 @@ impl From<FileInfo> for Value {
         UntaggedValue::row(r).retag(&f.tag)
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::Du;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Du {})
+    }
+}

crates/nu-cli/src/commands/each.rs

@@ -6,8 +6,8 @@ use crate::prelude::*;
 use futures::stream::once;
 use nu_errors::ShellError;
 use nu_protocol::{
-    hir::Block, hir::Expression, hir::SpannedExpression, hir::Synthetic, ReturnSuccess, Signature,
+    hir::Block, hir::Expression, hir::SpannedExpression, hir::Synthetic, Scope, Signature,
-    SyntaxShape,
+    SyntaxShape, UntaggedValue, Value,
 };
 
 pub struct Each;
@@ -17,6 +17,7 @@ pub struct EachArgs {
     block: Block,
 }
 
+#[async_trait]
 impl WholeStreamCommand for Each {
     fn name(&self) -> &str {
         "each"
@@ -34,19 +35,34 @@ impl WholeStreamCommand for Each {
         "Run a block on each row of the table."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        Ok(args.process_raw(registry, each)?.run())
+        each(args, registry).await
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[Example {
+        vec![
-            description: "Print the name of each file",
+            Example {
-            example: "ls | each { echo $it.name }",
+                description: "Echo the square of each integer",
-        }]
+                example: "echo [1 2 3] | each { echo $(= $it * $it) }",
+                result: Some(vec![
+                    UntaggedValue::int(1).into(),
+                    UntaggedValue::int(4).into(),
+                    UntaggedValue::int(9).into(),
+                ]),
+            },
+            Example {
+                description: "Echo the sum of each row",
+                example: "echo [[1 2] [3 4]] | each { echo $it | sum }",
+                result: Some(vec![
+                    UntaggedValue::int(3).into(),
+                    UntaggedValue::int(7).into(),
+                ]),
+            },
+        ]
     }
 }
 
@@ -60,50 +76,66 @@ fn is_expanded_it_usage(head: &SpannedExpression) -> bool {
     }
 }
 
-fn each(
+async fn process_row(
-    each_args: EachArgs,
+    block: Arc<Block>,
-    context: RunnableContext,
+    scope: Arc<Scope>,
-    raw_args: RawCommandArgs,
+    head: Arc<Box<SpannedExpression>>,
+    mut context: Arc<Context>,
+    input: Value,
 ) -> Result<OutputStream, ShellError> {
-    let block = each_args.block;
+    let input_clone = input.clone();
-    let scope = raw_args.call_info.scope.clone();
+    let input_stream = if is_expanded_it_usage(&head) {
-    let registry = context.registry.clone();
+        InputStream::empty()
-    let mut input_stream = context.input;
+    } else {
-    let stream = async_stream! {
+        once(async { Ok(input_clone) }).to_input_stream()
-        while let Some(input) = input_stream.next().await {
+    };
-            let mut context = Context::from_raw(&raw_args, &registry);
+    Ok(run_block(
+        &block,
+        Arc::make_mut(&mut context),
+        input_stream,
+        &input,
+        &scope.vars,
+        &scope.env,
+    )
+    .await?
+    .to_output_stream())
+}
 
-            let input_clone = input.clone();
+async fn each(
-            let input_stream = if is_expanded_it_usage(&raw_args.call_info.args.head) {
+    raw_args: CommandArgs,
-                InputStream::empty()
+    registry: &CommandRegistry,
-            } else {
+) -> Result<OutputStream, ShellError> {
-                once(async { Ok(input) }).to_input_stream()
+    let registry = registry.clone();
-            };
+    let head = Arc::new(raw_args.call_info.args.head.clone());
-
+    let scope = Arc::new(raw_args.call_info.scope.clone());
-            let result = run_block(
+    let context = Arc::new(Context::from_raw(&raw_args, &registry));
-                &block,
+    let (each_args, input): (EachArgs, _) = raw_args.process(&registry).await?;
-                &mut context,
+    let block = Arc::new(each_args.block);
-                input_stream,
+    Ok(input
-                &scope.clone().set_it(input_clone),
+        .then(move |input| {
-            ).await;
+            let block = block.clone();
-
+            let scope = scope.clone();
-            match result {
+            let head = head.clone();
-                Ok(mut stream) => {
+            let context = context.clone();
-                    while let Some(result) = stream.next().await {
+            async {
-                        yield Ok(ReturnSuccess::Value(result));
+                match process_row(block, scope, head, context, input).await {
-                    }
+                    Ok(s) => s,
-
+                    Err(e) => OutputStream::one(Err(e)),
-                    let errors = context.get_errors();
-                    if let Some(error) = errors.first() {
-                        yield Err(error.clone());
-                    }
-                }
-                Err(e) => {
-                    yield Err(e);
                 }
             }
-        }
+        })
-    };
+        .flatten()
-
+        .to_output_stream())
-    Ok(stream.to_output_stream())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Each;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Each {})
+    }
 }

crates/nu-cli/src/commands/echo.rs

@@ -1,7 +1,10 @@
 use crate::commands::WholeStreamCommand;
 use crate::prelude::*;
 use nu_errors::ShellError;
-use nu_protocol::{ReturnSuccess, Signature, SyntaxShape, UntaggedValue, Value};
+use nu_protocol::hir::Operator;
+use nu_protocol::{
+    Primitive, RangeInclusion, ReturnSuccess, Signature, SyntaxShape, UntaggedValue, Value,
+};
 
 pub struct Echo;
 
@@ -10,6 +13,7 @@ pub struct EchoArgs {
     pub rest: Vec<Value>,
 }
 
+#[async_trait]
 impl WholeStreamCommand for Echo {
     fn name(&self) -> &str {
         "echo"
@@ -23,56 +27,101 @@ impl WholeStreamCommand for Echo {
         "Echo the arguments back to the user."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, echo)?.run()
+        echo(args, registry)
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[
+        vec![
             Example {
                 description: "Put a hello message in the pipeline",
                 example: "echo 'hello'",
+                result: Some(vec![Value::from("hello")]),
             },
             Example {
                 description: "Print the value of the special '$nu' variable",
                 example: "echo $nu",
+                result: None,
             },
         ]
     }
 }
 
-fn echo(args: EchoArgs, _: RunnableContext) -> Result<OutputStream, ShellError> {
+fn echo(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
-    let mut output = vec![];
+    let registry = registry.clone();
+    let stream = async_stream! {
+        let (args, _): (EchoArgs, _) = args.process(&registry).await?;
 
-    for i in args.rest {
+        for i in args.rest {
-        match i.as_string() {
+            match i.as_string() {
-            Ok(s) => {
+                Ok(s) => {
-                output.push(Ok(ReturnSuccess::Value(
+                    yield Ok(ReturnSuccess::Value(
-                    UntaggedValue::string(s).into_value(i.tag.clone()),
+                        UntaggedValue::string(s).into_value(i.tag.clone()),
-                )));
+                    ));
-            }
+                }
-            _ => match i {
+                _ => match i {
-                Value {
+                    Value {
-                    value: UntaggedValue::Table(table),
+                        value: UntaggedValue::Table(table),
-                    ..
+                        ..
-                } => {
+                    } => {
-                    for value in table {
+                        for value in table {
-                        output.push(Ok(ReturnSuccess::Value(value.clone())));
+                            yield Ok(ReturnSuccess::Value(value.clone()));
+                        }
                     }
-                }
+                    Value {
-                _ => {
+                        value: UntaggedValue::Primitive(Primitive::Range(range)),
-                    output.push(Ok(ReturnSuccess::Value(i.clone())));
+                        tag
-                }
+                    } => {
-            },
+                        let mut current = range.from.0.item;
+                        while current != range.to.0.item {
+                            yield Ok(ReturnSuccess::Value(UntaggedValue::Primitive(current.clone()).into_value(&tag)));
+                            current = match crate::data::value::compute_values(Operator::Plus, &UntaggedValue::Primitive(current), &UntaggedValue::int(1)) {
+                                Ok(result) => match result {
+                                    UntaggedValue::Primitive(p) => p,
+                                    _ => {
+                                        yield Err(ShellError::unimplemented("Internal error: expected a primitive result from increment"));
+                                        return;
+                                    }
+                                },
+                                Err((left_type, right_type)) => {
+                                    yield Err(ShellError::coerce_error(
+                                        left_type.spanned(tag.span),
+                                        right_type.spanned(tag.span),
+                                    ));
+                                    return;
+                                }
+                            }
+                        }
+                        match range.to.1 {
+                            RangeInclusion::Inclusive => {
+                                yield Ok(ReturnSuccess::Value(UntaggedValue::Primitive(current.clone()).into_value(&tag)));
+                            }
+                            _ => {}
+                        }
+                    }
+                    _ => {
+                        yield Ok(ReturnSuccess::Value(i.clone()));
+                    }
+                },
+            }
         }
-    }
+    };
-
-    // TODO: This whole block can probably be replaced with `.map()`
-    let stream = futures::stream::iter(output);
 
     Ok(stream.to_output_stream())
 }
+
+#[cfg(test)]
+mod tests {
+    use super::Echo;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Echo {})
+    }
+}

crates/nu-cli/src/commands/enter.rs

@@ -16,6 +16,7 @@ pub struct EnterArgs {
     location: Tagged<PathBuf>,
 }
 
+#[async_trait]
 impl WholeStreamCommand for Enter {
     fn name(&self) -> &str {
         "enter"
@@ -33,66 +34,67 @@ impl WholeStreamCommand for Enter {
         "Create a new shell and begin at this path."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        Ok(args.process_raw(registry, enter)?.run())
+        enter(args, registry)
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[
+        vec![
             Example {
                 description: "Enter a path as a new shell",
                 example: "enter ../projectB",
+                result: None,
             },
             Example {
                 description: "Enter a file as a new shell",
                 example: "enter package.json",
+                result: None,
             },
         ]
     }
 }
 
-fn enter(
+fn enter(raw_args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
-    EnterArgs { location }: EnterArgs,
+    let registry = registry.clone();
-    RunnableContext {
+    let stream = async_stream! {
-        registry,
+        let scope = raw_args.call_info.scope.clone();
-        name: tag,
+        let shell_manager = raw_args.shell_manager.clone();
-        ..
+        let head = raw_args.call_info.args.head.clone();
-    }: RunnableContext,
+        let ctrl_c = raw_args.ctrl_c.clone();
-    raw_args: RawCommandArgs,
+        let current_errors = raw_args.current_errors.clone();
-) -> Result<OutputStream, ShellError> {
+        let host = raw_args.host.clone();
-    let location_string = location.display().to_string();
+        let tag = raw_args.call_info.name_tag.clone();
-    let location_clone = location_string.clone();
+        let (EnterArgs { location }, _) = raw_args.process(&registry).await?;
+        let location_string = location.display().to_string();
+        let location_clone = location_string.clone();
 
-    if location_string.starts_with("help") {
+        if location_string.starts_with("help") {
-        let spec = location_string.split(':').collect::<Vec<&str>>();
+            let spec = location_string.split(':').collect::<Vec<&str>>();
 
-        if spec.len() == 2 {
+            if spec.len() == 2 {
-            let (_, command) = (spec[0], spec[1]);
+                let (_, command) = (spec[0], spec[1]);
 
-            if registry.has(command) {
+                if registry.has(command) {
-                return Ok(vec![Ok(ReturnSuccess::Action(CommandAction::EnterHelpShell(
+                    yield Ok(ReturnSuccess::Action(CommandAction::EnterHelpShell(
-                    UntaggedValue::string(command).into_value(Tag::unknown()),
+                        UntaggedValue::string(command).into_value(Tag::unknown()),
-                )))]
+                    )));
-                .into());
+                    return;
+                }
             }
-        }
+            yield Ok(ReturnSuccess::Action(CommandAction::EnterHelpShell(
-        Ok(vec![Ok(ReturnSuccess::Action(CommandAction::EnterHelpShell(
+                UntaggedValue::nothing().into_value(Tag::unknown()),
-            UntaggedValue::nothing().into_value(Tag::unknown()),
+            )));
-        )))]
+        } else if location.is_dir() {
-        .into())
+            yield Ok(ReturnSuccess::Action(CommandAction::EnterShell(
-    } else if location.is_dir() {
+                location_clone,
-        Ok(vec![Ok(ReturnSuccess::Action(CommandAction::EnterShell(
+            )));
-            location_clone,
+        } else {
-        )))]
-        .into())
-    } else {
-        let stream = async_stream! {
             // If it's a file, attempt to open the file as a value and enter it
-            let cwd = raw_args.shell_manager.path();
+            let cwd = shell_manager.path();
 
             let full_path = std::path::PathBuf::from(cwd);
 
@@ -113,25 +115,26 @@ fn enter(
                             registry.get_command(&command_name)
                         {
                             let new_args = RawCommandArgs {
-                                host: raw_args.host,
+                                host,
-                                ctrl_c: raw_args.ctrl_c,
+                                ctrl_c,
-                                shell_manager: raw_args.shell_manager,
+                                current_errors,
+                                shell_manager,
                                 call_info: UnevaluatedCallInfo {
                                     args: nu_protocol::hir::Call {
-                                        head: raw_args.call_info.args.head,
+                                        head,
                                         positional: None,
                                         named: None,
                                         span: Span::unknown(),
                                         is_last: false,
                                     },
-                                    name_tag: raw_args.call_info.name_tag,
+                                    name_tag: tag.clone(),
-                                    scope: raw_args.call_info.scope.clone()
+                                    scope: scope.clone()
                                 },
                             };
                             let mut result = converter.run(
                                 new_args.with_input(vec![tagged_contents]),
                                 &registry,
-                            );
+                            ).await;
                             let result_vec: Vec<Result<ReturnSuccess, ShellError>> =
                                 result.drain_vec().await;
                             for res in result_vec {
@@ -162,7 +165,20 @@ fn enter(
                     yield Ok(ReturnSuccess::Action(CommandAction::EnterValueShell(tagged_contents)));
                 }
             }
-        };
+        }
-        Ok(stream.to_output_stream())
+    };
+
+    Ok(stream.to_output_stream())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Enter;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Enter {})
     }
 }

crates/nu-cli/src/commands/evaluate_by.rs

@@ -13,6 +13,7 @@ pub struct EvaluateByArgs {
     evaluate_with: Option<Tagged<String>>,
 }
 
+#[async_trait]
 impl WholeStreamCommand for EvaluateBy {
     fn name(&self) -> &str {
         "evaluate-by"
@@ -31,42 +32,52 @@ impl WholeStreamCommand for EvaluateBy {
         "Creates a new table with the data from the tables rows evaluated by the column given."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, evaluate_by)?.run()
+        evaluate_by(args, registry).await
     }
 }
 
-pub fn evaluate_by(
+pub async fn evaluate_by(
-    EvaluateByArgs { evaluate_with }: EvaluateByArgs,
+    args: CommandArgs,
-    RunnableContext { input, name, .. }: RunnableContext,
+    registry: &CommandRegistry,
 ) -> Result<OutputStream, ShellError> {
-    let stream = async_stream! {
+    let registry = registry.clone();
-        let values: Vec<Value> = input.collect().await;
+    let name = args.call_info.name_tag.clone();
+    let (EvaluateByArgs { evaluate_with }, mut input) = args.process(&registry).await?;
+    let values: Vec<Value> = input.collect().await;
 
-        if values.is_empty() {
+    if values.is_empty() {
-            yield Err(ShellError::labeled_error(
+        Err(ShellError::labeled_error(
-                    "Expected table from pipeline",
+            "Expected table from pipeline",
-                    "requires a table input",
+            "requires a table input",
-                    name
+            name,
-                ))
+        ))
+    } else {
+        let evaluate_with = if let Some(evaluator) = evaluate_with {
+            Some(evaluator.item().clone())
         } else {
+            None
+        };
 
-            let evaluate_with = if let Some(evaluator) = evaluate_with {
+        match evaluate(&values[0], evaluate_with, name) {
-                Some(evaluator.item().clone())
+            Ok(evaluated) => Ok(OutputStream::one(ReturnSuccess::value(evaluated))),
-            } else {
+            Err(err) => Err(err),
-                None
-            };
-
-            match evaluate(&values[0], evaluate_with, name) {
-                Ok(evaluated) => yield ReturnSuccess::value(evaluated),
-                Err(err) => yield Err(err)
-            }
         }
-    };
+    }
-
+}
-    Ok(stream.to_output_stream())
+
+#[cfg(test)]
+mod tests {
+    use super::EvaluateBy;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(EvaluateBy {})
+    }
 }

crates/nu-cli/src/commands/exit.rs

@@ -6,6 +6,7 @@ use nu_protocol::{CommandAction, ReturnSuccess, Signature};
 
 pub struct Exit;
 
+#[async_trait]
 impl WholeStreamCommand for Exit {
     fn name(&self) -> &str {
         "exit"
@@ -19,34 +20,54 @@ impl WholeStreamCommand for Exit {
         "Exit the current shell (or all shells)"
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        exit(args, registry)
+        exit(args, registry).await
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[
+        vec![
             Example {
                 description: "Exit the current shell",
                 example: "exit",
+                result: None,
             },
             Example {
                 description: "Exit all shells (exiting Nu)",
                 example: "exit --now",
+                result: None,
             },
         ]
     }
 }
 
-pub fn exit(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
+pub async fn exit(
-    let args = args.evaluate_once(registry)?;
+    args: CommandArgs,
+    registry: &CommandRegistry,
+) -> Result<OutputStream, ShellError> {
+    let registry = registry.clone();
+    let args = args.evaluate_once(&registry).await?;
 
-    if args.call_info.args.has("now") {
+    let command_action = if args.call_info.args.has("now") {
-        Ok(vec![Ok(ReturnSuccess::Action(CommandAction::Exit))].into())
+        CommandAction::Exit
     } else {
-        Ok(vec![Ok(ReturnSuccess::Action(CommandAction::LeaveShell))].into())
+        CommandAction::LeaveShell
+    };
+
+    Ok(OutputStream::one(ReturnSuccess::action(command_action)))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Exit;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Exit {})
     }
 }

crates/nu-cli/src/commands/first.rs

@@ -2,7 +2,7 @@ use crate::commands::WholeStreamCommand;
 use crate::context::CommandRegistry;
 use crate::prelude::*;
 use nu_errors::ShellError;
-use nu_protocol::{Signature, SyntaxShape};
+use nu_protocol::{Signature, SyntaxShape, UntaggedValue};
 use nu_source::Tagged;
 
 pub struct First;
@@ -12,6 +12,7 @@ pub struct FirstArgs {
     rows: Option<Tagged<usize>>,
 }
 
+#[async_trait]
 impl WholeStreamCommand for First {
     fn name(&self) -> &str {
         "first"
@@ -29,37 +30,53 @@ impl WholeStreamCommand for First {
         "Show only the first number of rows."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, first)?.run()
+        first(args, registry).await
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[
+        vec![
             Example {
                 description: "Return the first item of a list/table",
                 example: "echo [1 2 3] | first",
+                result: Some(vec![UntaggedValue::int(1).into()]),
             },
             Example {
                 description: "Return the first 2 items of a list/table",
                 example: "echo [1 2 3] | first 2",
+                result: Some(vec![
+                    UntaggedValue::int(1).into(),
+                    UntaggedValue::int(2).into(),
+                ]),
             },
         ]
     }
 }
 
-fn first(
+async fn first(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
-    FirstArgs { rows }: FirstArgs,
+    let registry = registry.clone();
-    context: RunnableContext,
+    let (FirstArgs { rows }, input) = args.process(&registry).await?;
-) -> Result<OutputStream, ShellError> {
     let rows_desired = if let Some(quantity) = rows {
         *quantity
     } else {
         1
     };
 
-    Ok(OutputStream::from_input(context.input.take(rows_desired)))
+    Ok(input.take(rows_desired).to_output_stream())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::First;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(First {})
+    }
 }

crates/nu-cli/src/commands/format.rs

@@ -1,10 +1,10 @@
 use crate::commands::WholeStreamCommand;
 use crate::context::CommandRegistry;
+use crate::evaluate::evaluate_baseline_expr;
 use crate::prelude::*;
 use nu_errors::ShellError;
-use nu_protocol::{ColumnPath, ReturnSuccess, Signature, SyntaxShape, UntaggedValue, Value};
+use nu_protocol::{ReturnSuccess, Signature, SyntaxShape, UntaggedValue};
 use nu_source::Tagged;
-use nu_value_ext::{as_column_path, get_data_by_column_path};
 use std::borrow::Borrow;
 
 pub struct Format;
@@ -14,6 +14,7 @@ pub struct FormatArgs {
     pattern: Tagged<String>,
 }
 
+#[async_trait]
 impl WholeStreamCommand for Format {
     fn name(&self) -> &str {
         "format"
@@ -31,72 +32,62 @@ impl WholeStreamCommand for Format {
         "Format columns into a string using a simple pattern."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, format_command)?.run()
+        format_command(args, registry)
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[Example {
+        vec![Example {
             description: "Print filenames with their sizes",
             example: "ls | format '{name}: {size}'",
+            result: None,
         }]
     }
 }
 
 fn format_command(
-    FormatArgs { pattern }: FormatArgs,
+    args: CommandArgs,
-    RunnableContext { input, .. }: RunnableContext,
+    registry: &CommandRegistry,
 ) -> Result<OutputStream, ShellError> {
-    let pattern_tag = pattern.tag.clone();
+    let registry = registry.clone();
-
-    let format_pattern = format(&pattern);
-    let commands = format_pattern;
-    let mut input = input;
-
     let stream = async_stream! {
+        let scope = args.call_info.scope.clone();
+        let (FormatArgs { pattern }, mut input) = args.process(&registry).await?;
+        let pattern_tag = pattern.tag.clone();
+
+        let format_pattern = format(&pattern);
+        let commands = format_pattern;
+
         while let Some(value) = input.next().await {
-            match value {
+            let mut output = String::new();
-                value
-                @
-                Value {
-                    value: UntaggedValue::Row(_),
-                    ..
-                } => {
-                    let mut output = String::new();
 
-                    for command in &commands {
+            for command in &commands {
-                        match command {
+                match command {
-                            FormatCommand::Text(s) => {
+                    FormatCommand::Text(s) => {
-                                output.push_str(&s);
+                        output.push_str(&s);
-                            }
+                    }
-                            FormatCommand::Column(c) => {
+                    FormatCommand::Column(c) => {
-                                let key = to_column_path(&c, &pattern_tag)?;
+                        // FIXME: use the correct spans
+                        let full_column_path = nu_parser::parse_full_column_path(&(c.to_string()).spanned(Span::unknown()), &registry);
 
-                                let fetcher = get_data_by_column_path(
+                        let result = evaluate_baseline_expr(&full_column_path.0, &registry, &value, &scope.vars, &scope.env).await;
-                                    &value,
-                                    &key,
-                                    Box::new(move |(_, _, error)| error),
-                                );
 
-                                if let Ok(c) = fetcher {
+                        if let Ok(c) = result {
-                                    output
+                            output
-                                        .push_str(&value::format_leaf(c.borrow()).plain_string(100_000))
+                                .push_str(&value::format_leaf(c.borrow()).plain_string(100_000))
-                                }
+                        } else {
-                                // That column doesn't match, so don't emit anything
+                            // That column doesn't match, so don't emit anything
-                            }
                         }
                     }
-
-                    yield ReturnSuccess::value(
-                        UntaggedValue::string(output).into_untagged_value())
                 }
-                _ => yield ReturnSuccess::value(
+            }
-                    UntaggedValue::string(String::new()).into_untagged_value()),
+
-            };
+            yield ReturnSuccess::value(
+                UntaggedValue::string(output).into_untagged_value())
         }
     };
 
@@ -148,26 +139,14 @@ fn format(input: &str) -> Vec<FormatCommand> {
     output
 }
 
-fn to_column_path(
+#[cfg(test)]
-    path_members: &str,
+mod tests {
-    tag: impl Into<Tag>,
+    use super::Format;
-) -> Result<Tagged<ColumnPath>, ShellError> {
-    let tag = tag.into();
 
-    as_column_path(
+    #[test]
-        &UntaggedValue::Table(
+    fn examples_work_as_expected() {
-            path_members
+        use crate::examples::test as test_examples;
-                .split('.')
-                .map(|x| {
-                    let member = match x.parse::<u64>() {
-                        Ok(v) => UntaggedValue::int(v),
-                        Err(_) => UntaggedValue::string(x),
-                    };
 
-                    member.into_value(&tag)
+        test_examples(Format {})
-                })
+    }
-                .collect(),
-        )
-        .into_value(&tag),
-    )
 }

crates/nu-cli/src/commands/from.rs

@@ -1,10 +1,11 @@
 use crate::commands::WholeStreamCommand;
 use crate::prelude::*;
 use nu_errors::ShellError;
-use nu_protocol::Signature;
+use nu_protocol::{ReturnSuccess, Signature, UntaggedValue};
 
 pub struct From;
 
+#[async_trait]
 impl WholeStreamCommand for From {
     fn name(&self) -> &str {
         "from"
@@ -18,11 +19,31 @@ impl WholeStreamCommand for From {
         "Parse content (string or binary) as a table (input format based on subcommand, like csv, ini, json, toml)"
     }
 
-    fn run(
+    async fn run(
         &self,
         _args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        Ok(crate::commands::help::get_help(&*self, registry).into())
+        let registry = registry.clone();
+        let stream = async_stream! {
+            yield Ok(ReturnSuccess::Value(
+                UntaggedValue::string(crate::commands::help::get_help(&From, &registry))
+                    .into_value(Tag::unknown()),
+            ));
+        };
+
+        Ok(stream.to_output_stream())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::From;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(From {})
     }
 }

crates/nu-cli/src/commands/from_bson.rs

@@ -8,6 +8,7 @@ use std::str::FromStr;
 
 pub struct FromBSON;
 
+#[async_trait]
 impl WholeStreamCommand for FromBSON {
     fn name(&self) -> &str {
         "from bson"
@@ -21,18 +22,19 @@ impl WholeStreamCommand for FromBSON {
         "Parse binary as .bson and create table."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        from_bson(args, registry)
+        from_bson(args, registry).await
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[Example {
+        vec![Example {
             description: "Convert bson data to a table",
             example: "open file.bin | from bson",
+            result: None,
         }]
     }
 }
@@ -206,27 +208,37 @@ pub fn from_bson_bytes_to_value(bytes: Vec<u8>, tag: impl Into<Tag>) -> Result<V
     convert_bson_value_to_nu_value(&Bson::Array(docs), tag)
 }
 
-fn from_bson(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
+async fn from_bson(
-    let args = args.evaluate_once(registry)?;
+    args: CommandArgs,
+    registry: &CommandRegistry,
+) -> Result<OutputStream, ShellError> {
+    let registry = registry.clone();
+    let args = args.evaluate_once(&registry).await?;
     let tag = args.name_tag();
     let input = args.input;
 
-    let stream = async_stream! {
+    let bytes = input.collect_binary(tag.clone()).await?;
-        let bytes = input.collect_binary(tag.clone()).await?;
 
-        match from_bson_bytes_to_value(bytes.item, tag.clone()) {
+    match from_bson_bytes_to_value(bytes.item, tag.clone()) {
-            Ok(x) => yield ReturnSuccess::value(x),
+        Ok(x) => Ok(OutputStream::one(ReturnSuccess::value(x))),
-            Err(_) => {
+        Err(_) => Err(ShellError::labeled_error_with_secondary(
-                yield Err(ShellError::labeled_error_with_secondary(
+            "Could not parse as BSON",
-                    "Could not parse as BSON",
+            "input cannot be parsed as BSON",
-                    "input cannot be parsed as BSON",
+            tag.clone(),
-                    tag.clone(),
+            "value originates from here",
-                    "value originates from here",
+            bytes.tag,
-                    bytes.tag,
+        )),
-                ))
+    }
-            }
+}
-        }
+
-    };
+#[cfg(test)]
-
+mod tests {
-    Ok(stream.to_output_stream())
+    use super::FromBSON;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(FromBSON {})
+    }
 }

crates/nu-cli/src/commands/from_csv.rs

@@ -12,6 +12,7 @@ pub struct FromCSVArgs {
     separator: Option<Value>,
 }
 
+#[async_trait]
 impl WholeStreamCommand for FromCSV {
     fn name(&self) -> &str {
         "from csv"
@@ -36,39 +37,49 @@ impl WholeStreamCommand for FromCSV {
         "Parse text as .csv and create table."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, from_csv)?.run()
+        from_csv(args, registry).await
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[
+        vec![
             Example {
                 description: "Convert comma-separated data to a table",
                 example: "open data.txt | from csv",
+                result: None,
             },
             Example {
                 description: "Convert comma-separated data to a table, ignoring headers",
                 example: "open data.txt | from csv --headerless",
+                result: None,
             },
             Example {
                 description: "Convert semicolon-separated data to a table",
                 example: "open data.txt | from csv --separator ';'",
+                result: None,
             },
         ]
     }
 }
 
-fn from_csv(
+async fn from_csv(
-    FromCSVArgs {
+    args: CommandArgs,
-        headerless,
+    registry: &CommandRegistry,
-        separator,
-    }: FromCSVArgs,
-    runnable_context: RunnableContext,
 ) -> Result<OutputStream, ShellError> {
+    let registry = registry.clone();
+    let name = args.call_info.name_tag.clone();
+
+    let (
+        FromCSVArgs {
+            headerless,
+            separator,
+        },
+        input,
+    ) = args.process(&registry).await?;
     let sep = match separator {
         Some(Value {
             value: UntaggedValue::Primitive(Primitive::String(s)),
@@ -92,5 +103,17 @@ fn from_csv(
         _ => ',',
     };
 
-    from_delimited_data(headerless, sep, "CSV", runnable_context)
+    from_delimited_data(headerless, sep, "CSV", input, name).await
+}
+
+#[cfg(test)]
+mod tests {
+    use super::FromCSV;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(FromCSV {})
+    }
 }

crates/nu-cli/src/commands/from_delimited_data.rs

@@ -1,7 +1,7 @@
 use crate::prelude::*;
 use csv::{ErrorKind, ReaderBuilder};
 use nu_errors::ShellError;
-use nu_protocol::{ReturnSuccess, TaggedDictBuilder, UntaggedValue, Value};
+use nu_protocol::{TaggedDictBuilder, UntaggedValue, Value};
 
 fn from_delimited_string_to_value(
     s: String,
@@ -41,44 +41,40 @@ fn from_delimited_string_to_value(
     Ok(UntaggedValue::Table(rows).into_value(&tag))
 }
 
-pub fn from_delimited_data(
+pub async fn from_delimited_data(
     headerless: bool,
     sep: char,
     format_name: &'static str,
-    RunnableContext { input, name, .. }: RunnableContext,
+    input: InputStream,
+    name: Tag,
 ) -> Result<OutputStream, ShellError> {
     let name_tag = name;
+    let concat_string = input.collect_string(name_tag.clone()).await?;
 
-    let stream = async_stream! {
+    match from_delimited_string_to_value(concat_string.item, headerless, sep, name_tag.clone()) {
-        let concat_string = input.collect_string(name_tag.clone()).await?;
+        Ok(x) => match x {
+            Value {
+                value: UntaggedValue::Table(list),
+                ..
+            } => Ok(futures::stream::iter(list).to_output_stream()),
+            x => Ok(OutputStream::one(x)),
+        },
+        Err(err) => {
+            let line_one = match pretty_csv_error(err) {
+                Some(pretty) => format!("Could not parse as {} ({})", format_name, pretty),
+                None => format!("Could not parse as {}", format_name),
+            };
+            let line_two = format!("input cannot be parsed as {}", format_name);
 
-        match from_delimited_string_to_value(concat_string.item, headerless, sep, name_tag.clone()) {
+            Err(ShellError::labeled_error_with_secondary(
-            Ok(x) => match x {
+                line_one,
-                Value { value: UntaggedValue::Table(list), .. } => {
+                line_two,
-                    for l in list {
+                name_tag.clone(),
-                        yield ReturnSuccess::value(l);
+                "value originates from here",
-                    }
+                concat_string.tag,
-                }
+            ))
-                x => yield ReturnSuccess::value(x),
-            },
-            Err(err) => {
-                let line_one = match pretty_csv_error(err) {
-                    Some(pretty) => format!("Could not parse as {} ({})", format_name,pretty),
-                    None => format!("Could not parse as {}", format_name),
-                };
-                let line_two = format!("input cannot be parsed as {}", format_name);
-                yield Err(ShellError::labeled_error_with_secondary(
-                    line_one,
-                    line_two,
-                    name_tag.clone(),
-                    "value originates from here",
-                    concat_string.tag,
-                ))
-            } ,
         }
-    };
+    }
-
-    Ok(stream.to_output_stream())
 }
 
 fn pretty_csv_error(err: csv::Error) -> Option<String> {

crates/nu-cli/src/commands/from_eml.rs

@@ -16,6 +16,7 @@ pub struct FromEMLArgs {
     preview_body: Option<Tagged<usize>>,
 }
 
+#[async_trait]
 impl WholeStreamCommand for FromEML {
     fn name(&self) -> &str {
         "from eml"
@@ -34,12 +35,12 @@ impl WholeStreamCommand for FromEML {
         "Parse text as .eml and create table."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, from_eml)?.run()
+        from_eml(args, registry).await
     }
 }
 
@@ -76,47 +77,64 @@ fn headerfieldvalue_to_value(tag: &Tag, value: &HeaderFieldValue) -> UntaggedVal
     }
 }
 
-fn from_eml(
+async fn from_eml(
-    eml_args: FromEMLArgs,
+    args: CommandArgs,
-    runnable_context: RunnableContext,
+    registry: &CommandRegistry,
 ) -> Result<OutputStream, ShellError> {
-    let input = runnable_context.input;
+    let tag = args.call_info.name_tag.clone();
-    let tag = runnable_context.name;
+    let registry = registry.clone();
+    let (eml_args, input): (FromEMLArgs, _) = args.process(&registry).await?;
+    let value = input.collect_string(tag.clone()).await?;
 
-    let stream = async_stream! {
+    let body_preview = eml_args
-        let value = input.collect_string(tag.clone()).await?;
+        .preview_body
+        .map(|b| b.item)
+        .unwrap_or(DEFAULT_BODY_PREVIEW);
 
-        let body_preview = eml_args.preview_body.map(|b| b.item).unwrap_or(DEFAULT_BODY_PREVIEW);
+    let eml = EmlParser::from_string(value.item)
-
-        let eml = EmlParser::from_string(value.item)
         .with_body_preview(body_preview)
         .parse()
-        .map_err(|_| ShellError::labeled_error("Could not parse .eml file", "could not parse .eml file", &tag))?;
+        .map_err(|_| {
+            ShellError::labeled_error(
+                "Could not parse .eml file",
+                "could not parse .eml file",
+                &tag,
+            )
+        })?;
 
-        let mut dict = TaggedDictBuilder::new(&tag);
+    let mut dict = TaggedDictBuilder::new(&tag);
 
-        if let Some(subj) = eml.subject {
+    if let Some(subj) = eml.subject {
-           dict.insert_untagged("Subject", UntaggedValue::string(subj));
+        dict.insert_untagged("Subject", UntaggedValue::string(subj));
-        }
+    }
 
-        if let Some(from) = eml.from {
+    if let Some(from) = eml.from {
-           dict.insert_untagged("From", headerfieldvalue_to_value(&tag, &from));
+        dict.insert_untagged("From", headerfieldvalue_to_value(&tag, &from));
-        }
+    }
 
-        if let Some(to) = eml.to {
+    if let Some(to) = eml.to {
-           dict.insert_untagged("To", headerfieldvalue_to_value(&tag, &to));
+        dict.insert_untagged("To", headerfieldvalue_to_value(&tag, &to));
-        }
+    }
 
-        for HeaderField{ name, value } in eml.headers.iter() {
+    for HeaderField { name, value } in eml.headers.iter() {
-           dict.insert_untagged(name, headerfieldvalue_to_value(&tag, &value));
+        dict.insert_untagged(name, headerfieldvalue_to_value(&tag, &value));
-        }
+    }
 
-        if let Some(body) = eml.body {
+    if let Some(body) = eml.body {
-           dict.insert_untagged("Body", UntaggedValue::string(body));
+        dict.insert_untagged("Body", UntaggedValue::string(body));
-        }
+    }
 
-        yield ReturnSuccess::value(dict.into_value());
+    Ok(OutputStream::one(ReturnSuccess::value(dict.into_value())))
-    };
+}
-
+
-    Ok(stream.to_output_stream())
+#[cfg(test)]
+mod tests {
+    use super::FromEML;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(FromEML {})
+    }
 }

crates/nu-cli/src/commands/from_ics.rs

@@ -9,6 +9,7 @@ use std::io::BufReader;
 
 pub struct FromIcs;
 
+#[async_trait]
 impl WholeStreamCommand for FromIcs {
     fn name(&self) -> &str {
         "from ics"
@@ -22,7 +23,7 @@ impl WholeStreamCommand for FromIcs {
         "Parse text as .ics and create table."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
@@ -32,11 +33,12 @@ impl WholeStreamCommand for FromIcs {
 }
 
 fn from_ics(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
-    let args = args.evaluate_once(registry)?;
+    let registry = registry.clone();
-    let tag = args.name_tag();
-    let input = args.input;
-
     let stream = async_stream! {
+        let args = args.evaluate_once(&registry).await?;
+        let tag = args.name_tag();
+        let input = args.input;
+
         let input_string = input.collect_string(tag.clone()).await?.item;
         let input_bytes = input_string.as_bytes();
         let buf_reader = BufReader::new(input_bytes);
@@ -238,3 +240,15 @@ fn params_to_value(params: Vec<(String, Vec<String>)>, tag: Tag) -> Value {
 
     row.into_value()
 }
+
+#[cfg(test)]
+mod tests {
+    use super::FromIcs;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(FromIcs {})
+    }
+}

crates/nu-cli/src/commands/from_ini.rs

@@ -1,11 +1,12 @@
 use crate::commands::WholeStreamCommand;
 use crate::prelude::*;
 use nu_errors::ShellError;
-use nu_protocol::{Primitive, ReturnSuccess, Signature, TaggedDictBuilder, UntaggedValue, Value};
+use nu_protocol::{Primitive, Signature, TaggedDictBuilder, UntaggedValue, Value};
 use std::collections::HashMap;
 
 pub struct FromINI;
 
+#[async_trait]
 impl WholeStreamCommand for FromINI {
     fn name(&self) -> &str {
         "from ini"
@@ -19,12 +20,12 @@ impl WholeStreamCommand for FromINI {
         "Parse text as .ini and create table"
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        from_ini(args, registry)
+        from_ini(args, registry).await
     }
 }
 
@@ -63,34 +64,42 @@ pub fn from_ini_string_to_value(
     Ok(convert_ini_top_to_nu_value(&v, tag))
 }
 
-fn from_ini(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
+async fn from_ini(
-    let args = args.evaluate_once(registry)?;
+    args: CommandArgs,
+    registry: &CommandRegistry,
+) -> Result<OutputStream, ShellError> {
+    let registry = registry.clone();
+    let args = args.evaluate_once(&registry).await?;
     let tag = args.name_tag();
     let input = args.input;
+    let concat_string = input.collect_string(tag.clone()).await?;
 
-    let stream = async_stream! {
+    match from_ini_string_to_value(concat_string.item, tag.clone()) {
-        let concat_string = input.collect_string(tag.clone()).await?;
+        Ok(x) => match x {
-
+            Value {
-        match from_ini_string_to_value(concat_string.item, tag.clone()) {
+                value: UntaggedValue::Table(list),
-            Ok(x) => match x {
+                ..
-                Value { value: UntaggedValue::Table(list), .. } => {
+            } => Ok(futures::stream::iter(list).to_output_stream()),
-                    for l in list {
+            x => Ok(OutputStream::one(x)),
-                        yield ReturnSuccess::value(l);
+        },
-                    }
+        Err(_) => Err(ShellError::labeled_error_with_secondary(
-                }
+            "Could not parse as INI",
-                x => yield ReturnSuccess::value(x),
+            "input cannot be parsed as INI",
-            },
+            &tag,
-            Err(_) => {
+            "value originates from here",
-                yield Err(ShellError::labeled_error_with_secondary(
+            concat_string.tag,
-                    "Could not parse as INI",
+        )),
-                    "input cannot be parsed as INI",
+    }
-                    &tag,
+}
-                    "value originates from here",
+
-                    concat_string.tag,
+#[cfg(test)]
-                ))
+mod tests {
-            }
+    use super::FromINI;
-        }
+
-    };
+    #[test]
-
+    fn examples_work_as_expected() {
-    Ok(stream.to_output_stream())
+        use crate::examples::test as test_examples;
+
+        test_examples(FromINI {})
+    }
 }

crates/nu-cli/src/commands/from_json.rs

@@ -10,6 +10,7 @@ pub struct FromJSONArgs {
     objects: bool,
 }
 
+#[async_trait]
 impl WholeStreamCommand for FromJSON {
     fn name(&self) -> &str {
         "from json"
@@ -27,12 +28,12 @@ impl WholeStreamCommand for FromJSON {
         "Parse text as .json and create table."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, from_json)?.run()
+        from_json(args, registry)
     }
 }
 
@@ -70,13 +71,12 @@ pub fn from_json_string_to_value(s: String, tag: impl Into<Tag>) -> serde_hjson:
     Ok(convert_json_value_to_nu_value(&v, tag))
 }
 
-fn from_json(
+fn from_json(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
-    FromJSONArgs { objects }: FromJSONArgs,
+    let name_tag = args.call_info.name_tag.clone();
-    RunnableContext { input, name, .. }: RunnableContext,
+    let registry = registry.clone();
-) -> Result<OutputStream, ShellError> {
-    let name_tag = name;
 
     let stream = async_stream! {
+        let (FromJSONArgs { objects }, mut input) = args.process(&registry).await?;
         let concat_string = input.collect_string(name_tag.clone()).await?;
 
         if objects {
@@ -131,3 +131,15 @@ fn from_json(
 
     Ok(stream.to_output_stream())
 }
+
+#[cfg(test)]
+mod tests {
+    use super::FromJSON;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(FromJSON {})
+    }
+}

crates/nu-cli/src/commands/from_ods.rs

@@ -13,6 +13,7 @@ pub struct FromODSArgs {
     headerless: bool,
 }
 
+#[async_trait]
 impl WholeStreamCommand for FromODS {
     fn name(&self) -> &str {
         "from ods"
@@ -30,25 +31,21 @@ impl WholeStreamCommand for FromODS {
         "Parse OpenDocument Spreadsheet(.ods) data and create table."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, from_ods)?.run()
+        from_ods(args, registry)
     }
 }
 
-fn from_ods(
+fn from_ods(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
-    FromODSArgs {
+    let tag = args.call_info.name_tag.clone();
-        headerless: _headerless,
+    let registry = registry.clone();
-    }: FromODSArgs,
-    runnable_context: RunnableContext,
-) -> Result<OutputStream, ShellError> {
-    let input = runnable_context.input;
-    let tag = runnable_context.name;
 
     let stream = async_stream! {
+        let (FromODSArgs { headerless: _headerless }, mut input) = args.process(&registry).await?;
         let bytes = input.collect_binary(tag.clone()).await?;
         let mut buf: Cursor<Vec<u8>> = Cursor::new(bytes.item);
         let mut ods = Ods::<_>::new(buf).map_err(|_| ShellError::labeled_error(
@@ -96,3 +93,15 @@ fn from_ods(
 
     Ok(stream.to_output_stream())
 }
+
+#[cfg(test)]
+mod tests {
+    use super::FromODS;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(FromODS {})
+    }
+}

crates/nu-cli/src/commands/from_sqlite.rs

@@ -1,13 +1,14 @@
 use crate::commands::WholeStreamCommand;
 use crate::prelude::*;
 use nu_errors::ShellError;
-use nu_protocol::{Primitive, ReturnSuccess, Signature, TaggedDictBuilder, UntaggedValue, Value};
+use nu_protocol::{Primitive, Signature, TaggedDictBuilder, UntaggedValue, Value};
 use rusqlite::{types::ValueRef, Connection, Row, NO_PARAMS};
 use std::io::Write;
 use std::path::Path;
 
 pub struct FromSQLite;
 
+#[async_trait]
 impl WholeStreamCommand for FromSQLite {
     fn name(&self) -> &str {
         "from sqlite"
@@ -21,17 +22,18 @@ impl WholeStreamCommand for FromSQLite {
         "Parse binary data as sqlite .db and create table."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        from_sqlite(args, registry)
+        from_sqlite(args, registry).await
     }
 }
 
 pub struct FromDB;
 
+#[async_trait]
 impl WholeStreamCommand for FromDB {
     fn name(&self) -> &str {
         "from db"
@@ -45,12 +47,12 @@ impl WholeStreamCommand for FromDB {
         "Parse binary data as db and create table."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        from_sqlite(args, registry)
+        from_sqlite(args, registry).await
     }
 }
 
@@ -63,6 +65,7 @@ pub fn convert_sqlite_file_to_nu_value(
     let mut meta_out = Vec::new();
     let mut meta_stmt = conn.prepare("select name from sqlite_master where type='table'")?;
     let mut meta_rows = meta_stmt.query(NO_PARAMS)?;
+
     while let Some(meta_row) = meta_rows.next()? {
         let table_name: String = meta_row.get(0)?;
         let mut meta_dict = TaggedDictBuilder::new(tag.clone());
@@ -132,34 +135,47 @@ pub fn from_sqlite_bytes_to_value(
     }
 }
 
-fn from_sqlite(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
+async fn from_sqlite(
-    let args = args.evaluate_once(registry)?;
+    args: CommandArgs,
+    registry: &CommandRegistry,
+) -> Result<OutputStream, ShellError> {
+    let registry = registry.clone();
+    let args = args.evaluate_once(&registry).await?;
     let tag = args.name_tag();
     let input = args.input;
 
-    let stream = async_stream! {
+    let bytes = input.collect_binary(tag.clone()).await?;
-        let bytes = input.collect_binary(tag.clone()).await?;
-        match from_sqlite_bytes_to_value(bytes.item, tag.clone()) {
-            Ok(x) => match x {
-                Value { value: UntaggedValue::Table(list), .. } => {
-                    for l in list {
-                        yield ReturnSuccess::value(l);
-                    }
-                }
-                _ => yield ReturnSuccess::value(x),
-            }
-            Err(err) => {
-                println!("{:?}", err);
-                yield Err(ShellError::labeled_error_with_secondary(
-                    "Could not parse as SQLite",
-                    "input cannot be parsed as SQLite",
-                    &tag,
-                    "value originates from here",
-                    bytes.tag,
-                ))
-            }
-        }
-    };
 
-    Ok(stream.to_output_stream())
+    match from_sqlite_bytes_to_value(bytes.item, tag.clone()) {
+        Ok(x) => match x {
+            Value {
+                value: UntaggedValue::Table(list),
+                ..
+            } => Ok(futures::stream::iter(list).to_output_stream()),
+            _ => Ok(OutputStream::one(x)),
+        },
+        Err(err) => {
+            println!("{:?}", err);
+
+            Err(ShellError::labeled_error_with_secondary(
+                "Could not parse as SQLite",
+                "input cannot be parsed as SQLite",
+                &tag,
+                "value originates from here",
+                bytes.tag,
+            ))
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::FromSQLite;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(FromSQLite {})
+    }
 }

crates/nu-cli/src/commands/from_ssv.rs

@@ -20,6 +20,7 @@ pub struct FromSSVArgs {
 const STRING_REPRESENTATION: &str = "from ssv";
 const DEFAULT_MINIMUM_SPACES: usize = 2;
 
+#[async_trait]
 impl WholeStreamCommand for FromSSV {
     fn name(&self) -> &str {
         STRING_REPRESENTATION
@@ -45,12 +46,12 @@ impl WholeStreamCommand for FromSSV {
         "Parse text as space-separated values and create a table. The default minimum number of spaces counted as a separator is 2."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, from_ssv)?.run()
+        from_ssv(args, registry)
     }
 }
 
@@ -250,15 +251,11 @@ fn from_ssv_string_to_value(
     Some(UntaggedValue::Table(rows).into_value(&tag))
 }
 
-fn from_ssv(
+fn from_ssv(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
-    FromSSVArgs {
+    let name = args.call_info.name_tag.clone();
-        headerless,
+    let registry = registry.clone();
-        aligned_columns,
-        minimum_spaces,
-    }: FromSSVArgs,
-    RunnableContext { input, name, .. }: RunnableContext,
-) -> Result<OutputStream, ShellError> {
     let stream = async_stream! {
+        let (FromSSVArgs { headerless, aligned_columns, minimum_spaces }, mut input) = args.process(&registry).await?;
         let concat_string = input.collect_string(name.clone()).await?;
         let split_at = match minimum_spaces {
             Some(number) => number.item,
@@ -489,4 +486,12 @@ mod tests {
         assert_eq!(aligned_columns_headerless, separator_headerless);
         assert_eq!(aligned_columns_with_headers, separator_with_headers);
     }
+
+    #[test]
+    fn examples_work_as_expected() {
+        use super::FromSSV;
+        use crate::examples::test as test_examples;
+
+        test_examples(FromSSV {})
+    }
 }

crates/nu-cli/src/commands/from_toml.rs

@@ -5,6 +5,7 @@ use nu_protocol::{Primitive, ReturnSuccess, Signature, TaggedDictBuilder, Untagg
 
 pub struct FromTOML;
 
+#[async_trait]
 impl WholeStreamCommand for FromTOML {
     fn name(&self) -> &str {
         "from toml"
@@ -18,7 +19,7 @@ impl WholeStreamCommand for FromTOML {
         "Parse text as .toml and create table."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
@@ -67,11 +68,12 @@ pub fn from_toml(
     args: CommandArgs,
     registry: &CommandRegistry,
 ) -> Result<OutputStream, ShellError> {
-    let args = args.evaluate_once(registry)?;
+    let registry = registry.clone();
-    let tag = args.name_tag();
-    let input = args.input;
-
     let stream = async_stream! {
+        let args = args.evaluate_once(&registry).await?;
+        let tag = args.name_tag();
+        let input = args.input;
+
         let concat_string = input.collect_string(tag.clone()).await?;
         match from_toml_string_to_value(concat_string.item, tag.clone()) {
             Ok(x) => match x {
@@ -96,3 +98,15 @@ pub fn from_toml(
 
     Ok(stream.to_output_stream())
 }
+
+#[cfg(test)]
+mod tests {
+    use super::FromTOML;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(FromTOML {})
+    }
+}

crates/nu-cli/src/commands/from_tsv.rs

@@ -11,6 +11,7 @@ pub struct FromTSVArgs {
     headerless: bool,
 }
 
+#[async_trait]
 impl WholeStreamCommand for FromTSV {
     fn name(&self) -> &str {
         "from tsv"
@@ -28,18 +29,34 @@ impl WholeStreamCommand for FromTSV {
         "Parse text as .tsv and create table."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, from_tsv)?.run()
+        from_tsv(args, registry).await
     }
 }
 
-fn from_tsv(
+async fn from_tsv(
-    FromTSVArgs { headerless }: FromTSVArgs,
+    args: CommandArgs,
-    runnable_context: RunnableContext,
+    registry: &CommandRegistry,
 ) -> Result<OutputStream, ShellError> {
-    from_delimited_data(headerless, '\t', "TSV", runnable_context)
+    let registry = registry.clone();
+    let name = args.call_info.name_tag.clone();
+    let (FromTSVArgs { headerless }, input) = args.process(&registry).await?;
+
+    from_delimited_data(headerless, '\t', "TSV", input, name).await
+}
+
+#[cfg(test)]
+mod tests {
+    use super::FromTSV;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(FromTSV {})
+    }
 }

crates/nu-cli/src/commands/from_url.rs

@@ -5,6 +5,7 @@ use nu_protocol::{ReturnSuccess, Signature, TaggedDictBuilder, UntaggedValue};
 
 pub struct FromURL;
 
+#[async_trait]
 impl WholeStreamCommand for FromURL {
     fn name(&self) -> &str {
         "from url"
@@ -18,46 +19,56 @@ impl WholeStreamCommand for FromURL {
         "Parse url-encoded string as a table."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        from_url(args, registry)
+        from_url(args, registry).await
     }
 }
 
-fn from_url(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
+async fn from_url(
-    let args = args.evaluate_once(registry)?;
+    args: CommandArgs,
+    registry: &CommandRegistry,
+) -> Result<OutputStream, ShellError> {
+    let registry = registry.clone();
+    let args = args.evaluate_once(&registry).await?;
     let tag = args.name_tag();
     let input = args.input;
 
-    let stream = async_stream! {
+    let concat_string = input.collect_string(tag.clone()).await?;
-        let concat_string = input.collect_string(tag.clone()).await?;
 
-        let result = serde_urlencoded::from_str::<Vec<(String, String)>>(&concat_string.item);
+    let result = serde_urlencoded::from_str::<Vec<(String, String)>>(&concat_string.item);
 
-        match result {
+    match result {
-            Ok(result) => {
+        Ok(result) => {
-                let mut row = TaggedDictBuilder::new(tag);
+            let mut row = TaggedDictBuilder::new(tag);
 
-                for (k,v) in result {
+            for (k, v) in result {
-                    row.insert_untagged(k, UntaggedValue::string(v));
+                row.insert_untagged(k, UntaggedValue::string(v));
-                }
-
-                yield ReturnSuccess::value(row.into_value());
-            }
-            _ => {
-                yield Err(ShellError::labeled_error_with_secondary(
-                    "String not compatible with url-encoding",
-                    "input not url-encoded",
-                    tag,
-                    "value originates from here",
-                    concat_string.tag,
-                ));
             }
+
+            Ok(OutputStream::one(ReturnSuccess::value(row.into_value())))
         }
-    };
+        _ => Err(ShellError::labeled_error_with_secondary(
-
+            "String not compatible with url-encoding",
-    Ok(stream.to_output_stream())
+            "input not url-encoded",
+            tag,
+            "value originates from here",
+            concat_string.tag,
+        )),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::FromURL;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(FromURL {})
+    }
 }

crates/nu-cli/src/commands/from_vcf.rs

@@ -9,6 +9,7 @@ use std::io::BufReader;
 
 pub struct FromVcf;
 
+#[async_trait]
 impl WholeStreamCommand for FromVcf {
     fn name(&self) -> &str {
         "from vcf"
@@ -22,39 +23,47 @@ impl WholeStreamCommand for FromVcf {
         "Parse text as .vcf and create table."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        from_vcf(args, registry)
+        from_vcf(args, registry).await
     }
 }
 
-fn from_vcf(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
+async fn from_vcf(
-    let args = args.evaluate_once(registry)?;
+    args: CommandArgs,
+    registry: &CommandRegistry,
+) -> Result<OutputStream, ShellError> {
+    let registry = registry.clone();
+    let args = args.evaluate_once(&registry).await?;
     let tag = args.name_tag();
     let input = args.input;
 
-    let stream = async_stream! {
+    let input_string = input.collect_string(tag.clone()).await?.item;
-        let input_string = input.collect_string(tag.clone()).await?.item;
+    let input_bytes = input_string.as_bytes();
-        let input_bytes = input_string.as_bytes();
+    let buf_reader = BufReader::new(input_bytes);
-        let buf_reader = BufReader::new(input_bytes);
+    let parser = ical::VcardParser::new(buf_reader);
-        let parser = ical::VcardParser::new(buf_reader);
 
-        for contact in parser {
+    let mut values_vec_deque = VecDeque::new();
-            match contact {
+
-                Ok(c) => yield ReturnSuccess::value(contact_to_value(c, tag.clone())),
+    for contact in parser {
-                Err(_) => yield Err(ShellError::labeled_error(
+        match contact {
+            Ok(c) => {
+                values_vec_deque.push_back(ReturnSuccess::value(contact_to_value(c, tag.clone())))
+            }
+            Err(_) => {
+                return Err(ShellError::labeled_error(
                     "Could not parse as .vcf",
                     "input cannot be parsed as .vcf",
-                    tag.clone()
+                    tag.clone(),
-                )),
+                ))
             }
         }
-    };
+    }
 
-    Ok(stream.to_output_stream())
+    Ok(futures::stream::iter(values_vec_deque).to_output_stream())
 }
 
 fn contact_to_value(contact: VcardContact, tag: Tag) -> Value {
@@ -100,3 +109,15 @@ fn params_to_value(params: Vec<(String, Vec<String>)>, tag: Tag) -> Value {
 
     row.into_value()
 }
+
+#[cfg(test)]
+mod tests {
+    use super::FromVcf;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(FromVcf {})
+    }
+}

crates/nu-cli/src/commands/from_xlsx.rs

@@ -13,6 +13,7 @@ pub struct FromXLSXArgs {
     headerless: bool,
 }
 
+#[async_trait]
 impl WholeStreamCommand for FromXLSX {
     fn name(&self) -> &str {
         "from xlsx"
@@ -30,25 +31,20 @@ impl WholeStreamCommand for FromXLSX {
         "Parse binary Excel(.xlsx) data and create table."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, from_xlsx)?.run()
+        from_xlsx(args, registry)
     }
 }
 
-fn from_xlsx(
+fn from_xlsx(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
-    FromXLSXArgs {
+    let tag = args.call_info.name_tag.clone();
-        headerless: _headerless,
+    let registry = registry.clone();
-    }: FromXLSXArgs,
-    runnable_context: RunnableContext,
-) -> Result<OutputStream, ShellError> {
-    let input = runnable_context.input;
-    let tag = runnable_context.name;
-
     let stream = async_stream! {
+        let (FromXLSXArgs { headerless: _headerless }, mut input) = args.process(&registry).await?;
         let value = input.collect_binary(tag.clone()).await?;
 
         let mut buf: Cursor<Vec<u8>> = Cursor::new(value.item);
@@ -97,3 +93,15 @@ fn from_xlsx(
 
     Ok(stream.to_output_stream())
 }
+
+#[cfg(test)]
+mod tests {
+    use super::FromXLSX;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(FromXLSX {})
+    }
+}

crates/nu-cli/src/commands/from_xml.rs

@@ -5,6 +5,7 @@ use nu_protocol::{Primitive, ReturnSuccess, Signature, TaggedDictBuilder, Untagg
 
 pub struct FromXML;
 
+#[async_trait]
 impl WholeStreamCommand for FromXML {
     fn name(&self) -> &str {
         "from xml"
@@ -18,7 +19,7 @@ impl WholeStreamCommand for FromXML {
         "Parse text as .xml and create table."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
@@ -99,11 +100,12 @@ pub fn from_xml_string_to_value(s: String, tag: impl Into<Tag>) -> Result<Value,
 }
 
 fn from_xml(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
-    let args = args.evaluate_once(registry)?;
+    let registry = registry.clone();
-    let tag = args.name_tag();
-    let input = args.input;
-
     let stream = async_stream! {
+        let args = args.evaluate_once(&registry).await?;
+        let tag = args.name_tag();
+        let input = args.input;
+
         let concat_string = input.collect_string(tag.clone()).await?;
 
         match from_xml_string_to_value(concat_string.item, tag.clone()) {
@@ -300,4 +302,12 @@ mod tests {
 
         Ok(())
     }
+
+    #[test]
+    fn examples_work_as_expected() {
+        use super::FromXML;
+        use crate::examples::test as test_examples;
+
+        test_examples(FromXML {})
+    }
 }

crates/nu-cli/src/commands/from_yaml.rs

@@ -1,10 +1,11 @@
 use crate::commands::WholeStreamCommand;
 use crate::prelude::*;
 use nu_errors::ShellError;
-use nu_protocol::{Primitive, ReturnSuccess, Signature, TaggedDictBuilder, UntaggedValue, Value};
+use nu_protocol::{Primitive, Signature, TaggedDictBuilder, UntaggedValue, Value};
 
 pub struct FromYAML;
 
+#[async_trait]
 impl WholeStreamCommand for FromYAML {
     fn name(&self) -> &str {
         "from yaml"
@@ -18,17 +19,18 @@ impl WholeStreamCommand for FromYAML {
         "Parse text as .yaml/.yml and create table."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        from_yaml(args, registry)
+        from_yaml(args, registry).await
     }
 }
 
 pub struct FromYML;
 
+#[async_trait]
 impl WholeStreamCommand for FromYML {
     fn name(&self) -> &str {
         "from yml"
@@ -42,12 +44,12 @@ impl WholeStreamCommand for FromYML {
         "Parse text as .yaml/.yml and create table."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        from_yaml(args, registry)
+        from_yaml(args, registry).await
     }
 }
 
@@ -118,34 +120,43 @@ pub fn from_yaml_string_to_value(s: String, tag: impl Into<Tag>) -> Result<Value
     Ok(convert_yaml_value_to_nu_value(&v, tag)?)
 }
 
-fn from_yaml(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
+async fn from_yaml(
-    let args = args.evaluate_once(registry)?;
+    args: CommandArgs,
+    registry: &CommandRegistry,
+) -> Result<OutputStream, ShellError> {
+    let registry = registry.clone();
+    let args = args.evaluate_once(&registry).await?;
     let tag = args.name_tag();
     let input = args.input;
 
-    let stream = async_stream! {
+    let concat_string = input.collect_string(tag.clone()).await?;
-        let concat_string = input.collect_string(tag.clone()).await?;
 
-        match from_yaml_string_to_value(concat_string.item, tag.clone()) {
+    match from_yaml_string_to_value(concat_string.item, tag.clone()) {
-            Ok(x) => match x {
+        Ok(x) => match x {
-                Value { value: UntaggedValue::Table(list), .. } => {
+            Value {
-                    for l in list {
+                value: UntaggedValue::Table(list),
-                        yield ReturnSuccess::value(l);
+                ..
-                    }
+            } => Ok(futures::stream::iter(list).to_output_stream()),
-                }
+            x => Ok(OutputStream::one(x)),
-                x => yield ReturnSuccess::value(x),
+        },
-            },
+        Err(_) => Err(ShellError::labeled_error_with_secondary(
-            Err(_) => {
+            "Could not parse as YAML",
-                yield Err(ShellError::labeled_error_with_secondary(
+            "input cannot be parsed as YAML",
-                    "Could not parse as YAML",
+            &tag,
-                    "input cannot be parsed as YAML",
+            "value originates from here",
-                    &tag,
+            &concat_string.tag,
-                    "value originates from here",
+        )),
-                    &concat_string.tag,
+    }
-                ))
+}
-            }
+
-        }
+#[cfg(test)]
-    };
+mod tests {
-
+    use super::FromYAML;
-    Ok(stream.to_output_stream())
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(FromYAML {})
+    }
 }

crates/nu-cli/src/commands/get.rs

@@ -4,8 +4,8 @@ use indexmap::set::IndexSet;
 use log::trace;
 use nu_errors::ShellError;
 use nu_protocol::{
-    did_you_mean, ColumnPath, PathMember, Primitive, ReturnSuccess, ReturnValue, Signature,
+    did_you_mean, ColumnPath, PathMember, Primitive, ReturnSuccess, Signature, SyntaxShape,
-    SyntaxShape, UnspannedPathMember, UntaggedValue, Value,
+    UnspannedPathMember, UntaggedValue, Value,
 };
 use nu_source::span_for_spanned_list;
 use nu_value_ext::get_data_by_column_path;
@@ -17,6 +17,7 @@ pub struct GetArgs {
     rest: Vec<ColumnPath>,
 }
 
+#[async_trait]
 impl WholeStreamCommand for Get {
     fn name(&self) -> &str {
         "get"
@@ -33,23 +34,25 @@ impl WholeStreamCommand for Get {
         "Open given cells as text."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, get)?.run()
+        get(args, registry)
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[
+        vec![
             Example {
                 description: "Extract the name of files as a list",
                 example: "ls | get name",
+                result: None,
             },
             Example {
                 description: "Extract the cpu list from the sys information",
                 example: "sys | get cpu",
+                result: None,
             },
         ]
     }
@@ -189,30 +192,21 @@ pub fn get_column_path(path: &ColumnPath, obj: &Value) -> Result<Value, ShellErr
     )
 }
 
-pub fn get(
+pub fn get(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
-    GetArgs { rest: mut fields }: GetArgs,
+    let registry = registry.clone();
-    RunnableContext { mut input, .. }: RunnableContext,
+    let stream = async_stream! {
-) -> Result<OutputStream, ShellError> {
+        let (GetArgs { rest: mut fields }, mut input) = args.process(&registry).await?;
-    if fields.is_empty() {
+        if fields.is_empty() {
-        let stream = async_stream! {
             let mut vec = input.drain_vec().await;
 
             let descs = nu_protocol::merge_descriptors(&vec);
             for desc in descs {
                 yield ReturnSuccess::value(desc);
             }
-        };
+        } else {
-
+            let member = fields.remove(0);
-        let stream: BoxStream<'static, ReturnValue> = stream.boxed();
+            trace!("get {:?} {:?}", member, fields);
-
+            while let Some(item) = input.next().await {
-        Ok(stream.to_output_stream())
-    } else {
-        let member = fields.remove(0);
-        trace!("get {:?} {:?}", member, fields);
-        let stream = input
-            .map(move |item| {
-                let mut result = VecDeque::new();
-
                 let member = vec![member.clone()];
 
                 let column_paths = vec![&member, &fields]
@@ -230,25 +224,34 @@ pub fn get(
                                 ..
                             } => {
                                 for item in rows {
-                                    result.push_back(ReturnSuccess::value(item.clone()));
+                                    yield ReturnSuccess::value(item.clone());
                                 }
                             }
                             Value {
                                 value: UntaggedValue::Primitive(Primitive::Nothing),
                                 ..
                             } => {}
-                            other => result.push_back(ReturnSuccess::value(other.clone())),
+                            other => yield ReturnSuccess::value(other.clone()),
                         },
-                        Err(reason) => result.push_back(ReturnSuccess::value(
+                        Err(reason) => yield ReturnSuccess::value(
                             UntaggedValue::Error(reason).into_untagged_value(),
-                        )),
+                        ),
                     }
                 }
+            }
+        }
+    };
+    Ok(stream.to_output_stream())
+}
 
-                futures::stream::iter(result)
+#[cfg(test)]
-            })
+mod tests {
-            .flatten();
+    use super::Get;
 
-        Ok(stream.to_output_stream())
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Get {})
     }
 }

crates/nu-cli/src/commands/group_by.rs

@@ -1,119 +1,97 @@
 use crate::commands::WholeStreamCommand;
 use crate::prelude::*;
+use indexmap::indexmap;
 use nu_errors::ShellError;
-use nu_protocol::{ReturnSuccess, Signature, SyntaxShape, Value};
+use nu_protocol::{ReturnSuccess, Signature, SyntaxShape, UntaggedValue, Value};
 use nu_source::Tagged;
 
 pub struct GroupBy;
 
 #[derive(Deserialize)]
 pub struct GroupByArgs {
-    column_name: Tagged<String>,
+    column_name: Option<Tagged<String>>,
-    date: Tagged<bool>,
-    format: Option<Tagged<String>>,
 }
 
+#[async_trait]
 impl WholeStreamCommand for GroupBy {
     fn name(&self) -> &str {
         "group-by"
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("group-by")
+        Signature::build("group-by").optional(
-            .required(
+            "column_name",
-                "column_name",
+            SyntaxShape::String,
-                SyntaxShape::String,
+            "the name of the column to group by",
-                "the name of the column to group by",
+        )
-            )
-            .named(
-                "format",
-                SyntaxShape::String,
-                "Specify date and time formatting",
-                Some('f'),
-            )
-            .switch("date", "by date", Some('d'))
     }
 
     fn usage(&self) -> &str {
         "Creates a new table with the data from the table rows grouped by the column given."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, group_by)?.run()
+        group_by(args, registry).await
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[Example {
+        vec![
-            description: "Group files by type",
+            Example {
-            example: "ls | group-by type",
+                description: "Group items by type",
-        }]
+                example: r#"ls | group-by type"#,
+                result: None,
+            },
+            Example {
+                description: "Group items by their value",
+                example: "echo [1 3 1 3 2 1 1] | group-by",
+                result: Some(vec![UntaggedValue::row(indexmap! {
+                    "1".to_string() => UntaggedValue::Table(vec![
+                        UntaggedValue::int(1).into(),
+                        UntaggedValue::int(1).into(),
+                        UntaggedValue::int(1).into(),
+                        UntaggedValue::int(1).into(),
+                    ]).into(),
+
+                    "3".to_string() => UntaggedValue::Table(vec![
+                        UntaggedValue::int(3).into(),
+                        UntaggedValue::int(3).into(),
+                    ]).into(),
+
+                    "2".to_string() => UntaggedValue::Table(vec![
+                        UntaggedValue::int(2).into(),
+                    ]).into(),
+                })
+                .into()]),
+            },
+        ]
     }
 }
 
-enum Grouper {
+pub async fn group_by(
-    Default,
+    args: CommandArgs,
-    ByDate(Option<String>),
+    registry: &CommandRegistry,
-}
-
-pub fn group_by(
-    GroupByArgs {
-        column_name,
-        date,
-        format,
-    }: GroupByArgs,
-    RunnableContext { input, name, .. }: RunnableContext,
 ) -> Result<OutputStream, ShellError> {
-    let stream = async_stream! {
+    let registry = registry.clone();
-        let values: Vec<Value> = input.collect().await;
+    let name = args.call_info.name_tag.clone();
+    let (GroupByArgs { column_name }, input) = args.process(&registry).await?;
+    let values: Vec<Value> = input.collect().await;
 
-        if values.is_empty() {
+    if values.is_empty() {
-            yield Err(ShellError::labeled_error(
+        Err(ShellError::labeled_error(
-                    "Expected table from pipeline",
+            "Expected table from pipeline",
-                    "requires a table input",
+            "requires a table input",
-                    column_name.span()
+            name,
-                ))
+        ))
-        } else {
+    } else {
-
+        match crate::utils::data::group(column_name, &values, None, &name) {
-            let grouper = if let Tagged { item: true, tag } = date {
+            Ok(grouped) => Ok(OutputStream::one(ReturnSuccess::value(grouped))),
-                if let Some(Tagged { item: fmt, tag }) = format {
+            Err(err) => Err(err),
-                    Grouper::ByDate(Some(fmt))
-                } else {
-                    Grouper::ByDate(None)
-                }
-            } else {
-                Grouper::Default
-            };
-
-            match grouper {
-                Grouper::Default => {
-                    match crate::utils::data::group(column_name, &values, None, &name) {
-                        Ok(grouped) => yield ReturnSuccess::value(grouped),
-                        Err(err) => yield Err(err),
-                    }
-                }
-                Grouper::ByDate(None) => {
-                    match crate::utils::data::group(column_name, &values, Some(Box::new(|row: &Value| row.format("%Y-%b-%d"))), &name) {
-                        Ok(grouped) => yield ReturnSuccess::value(grouped),
-                        Err(err) => yield Err(err),
-                    }
-                }
-                Grouper::ByDate(Some(fmt)) => {
-                    match crate::utils::data::group(column_name, &values, Some(Box::new(move |row: &Value| {
-                        row.format(&fmt)
-                    })), &name) {
-                        Ok(grouped) => yield ReturnSuccess::value(grouped),
-                        Err(err) => yield Err(err),
-                    }
-                }
-            }
         }
-    };
+    }
-
-    Ok(stream.to_output_stream())
 }
 
 pub fn group(
@@ -121,7 +99,7 @@ pub fn group(
     values: Vec<Value>,
     tag: impl Into<Tag>,
 ) -> Result<Value, ShellError> {
-    crate::utils::data::group(column_name.clone(), &values, None, tag)
+    crate::utils::data::group(Some(column_name.clone()), &values, None, tag)
 }
 
 #[cfg(test)]
@@ -231,4 +209,12 @@ mod tests {
 
         Ok(())
     }
+
+    #[test]
+    fn examples_work_as_expected() {
+        use super::GroupBy;
+        use crate::examples::test as test_examples;
+
+        test_examples(GroupBy {})
+    }
 }

crates/nu-cli/src/commands/group_by_date.rs

@@ -0,0 +1,126 @@
+use crate::commands::WholeStreamCommand;
+use crate::prelude::*;
+use nu_errors::ShellError;
+use nu_protocol::{ReturnSuccess, Signature, SyntaxShape, Value};
+use nu_source::Tagged;
+
+pub struct GroupByDate;
+
+#[derive(Deserialize)]
+pub struct GroupByDateArgs {
+    column_name: Option<Tagged<String>>,
+    format: Option<Tagged<String>>,
+}
+
+#[async_trait]
+impl WholeStreamCommand for GroupByDate {
+    fn name(&self) -> &str {
+        "group-by date"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("group-by date")
+            .optional(
+                "column_name",
+                SyntaxShape::String,
+                "the name of the column to group by",
+            )
+            .named(
+                "format",
+                SyntaxShape::String,
+                "Specify date and time formatting",
+                Some('f'),
+            )
+    }
+
+    fn usage(&self) -> &str {
+        "Creates a new table with the data from the table rows grouped by the column given."
+    }
+
+    async fn run(
+        &self,
+        args: CommandArgs,
+        registry: &CommandRegistry,
+    ) -> Result<OutputStream, ShellError> {
+        group_by_date(args, registry).await
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![Example {
+            description: "Group files by type",
+            example: "ls | group-by date --format '%d/%m/%Y'",
+            result: None,
+        }]
+    }
+}
+
+enum Grouper {
+    ByDate(Option<String>),
+}
+
+pub async fn group_by_date(
+    args: CommandArgs,
+    registry: &CommandRegistry,
+) -> Result<OutputStream, ShellError> {
+    let registry = registry.clone();
+    let name = args.call_info.name_tag.clone();
+    let (
+        GroupByDateArgs {
+            column_name,
+            format,
+        },
+        input,
+    ) = args.process(&registry).await?;
+    let values: Vec<Value> = input.collect().await;
+
+    if values.is_empty() {
+        Err(ShellError::labeled_error(
+            "Expected table from pipeline",
+            "requires a table input",
+            name,
+        ))
+    } else {
+        let grouper = if let Some(Tagged { item: fmt, tag: _ }) = format {
+            Grouper::ByDate(Some(fmt))
+        } else {
+            Grouper::ByDate(None)
+        };
+
+        match grouper {
+            Grouper::ByDate(None) => {
+                match crate::utils::data::group(
+                    column_name,
+                    &values,
+                    Some(Box::new(|row: &Value| row.format("%Y-%b-%d"))),
+                    &name,
+                ) {
+                    Ok(grouped) => Ok(OutputStream::one(ReturnSuccess::value(grouped))),
+                    Err(err) => Err(err),
+                }
+            }
+            Grouper::ByDate(Some(fmt)) => {
+                match crate::utils::data::group(
+                    column_name,
+                    &values,
+                    Some(Box::new(move |row: &Value| row.format(&fmt))),
+                    &name,
+                ) {
+                    Ok(grouped) => Ok(OutputStream::one(ReturnSuccess::value(grouped))),
+                    Err(err) => Err(err),
+                }
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::GroupByDate;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(GroupByDate {})
+    }
+}

crates/nu-cli/src/commands/headers.rs

@@ -8,9 +8,8 @@ use nu_protocol::Dictionary;
 use nu_protocol::{ReturnSuccess, Signature, UntaggedValue, Value};
 
 pub struct Headers;
-#[derive(Deserialize)]
-pub struct HeadersArgs {}
 
+#[async_trait]
 impl WholeStreamCommand for Headers {
     fn name(&self) -> &str {
         "headers"
@@ -24,27 +23,26 @@ impl WholeStreamCommand for Headers {
         "Use the first row of the table as column names"
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, headers)?.run()
+        headers(args, registry)
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[Example {
+        vec![Example {
             description: "Create headers for a raw string",
-            example: "echo \"a b c|1 2 3\" | split-row \"|\" | split-column \" \" | headers",
+            example: r#"echo "a b c|1 2 3" | split row "|" | split column " " | headers"#,
+            result: None,
         }]
     }
 }
 
-pub fn headers(
+pub fn headers(args: CommandArgs, _registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
-    HeadersArgs {}: HeadersArgs,
-    RunnableContext { input, .. }: RunnableContext,
-) -> Result<OutputStream, ShellError> {
     let stream = async_stream! {
+        let mut input = args.input;
         let rows: Vec<Value> = input.collect().await;
 
         if rows.len() < 1 {
@@ -88,3 +86,15 @@ pub fn headers(
 
     Ok(stream.to_output_stream())
 }
+
+#[cfg(test)]
+mod tests {
+    use super::Headers;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Headers {})
+    }
+}

crates/nu-cli/src/commands/help.rs

@@ -17,6 +17,7 @@ pub struct HelpArgs {
     rest: Vec<Tagged<String>>,
 }
 
+#[async_trait]
 impl WholeStreamCommand for Help {
     fn name(&self) -> &str {
         "help"
@@ -30,77 +31,75 @@ impl WholeStreamCommand for Help {
         "Display help information about commands."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, help)?.run()
+        help(args, registry)
     }
 }
 
-fn help(
+fn help(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
-    HelpArgs { rest }: HelpArgs,
+    let registry = registry.clone();
-    RunnableContext { registry, name, .. }: RunnableContext,
+    let name = args.call_info.name_tag.clone();
-) -> Result<OutputStream, ShellError> {
+    let stream = async_stream! {
-    if let Some(document) = rest.get(0) {
+        let (HelpArgs { rest }, mut input) = args.process(&registry).await?;
-        let mut help = VecDeque::new();
+        if let Some(document) = rest.get(0) {
-        if document.item == "commands" {
+            if document.item == "commands" {
-            let mut sorted_names = registry.names();
+                let mut sorted_names = registry.names();
-            sorted_names.sort();
+                sorted_names.sort();
-            for cmd in sorted_names {
+                for cmd in sorted_names {
-                // If it's a subcommand, don't list it during the commands list
+                    // If it's a subcommand, don't list it during the commands list
-                if cmd.contains(' ') {
+                    if cmd.contains(' ') {
-                    continue;
+                        continue;
-                }
+                    }
-                let mut short_desc = TaggedDictBuilder::new(name.clone());
+                    let mut short_desc = TaggedDictBuilder::new(name.clone());
-                let document_tag = document.tag.clone();
+                    let document_tag = document.tag.clone();
-                let value = command_dict(
+                    let value = command_dict(
-                    registry.get_command(&cmd).ok_or_else(|| {
+                        registry.get_command(&cmd).ok_or_else(|| {
-                        ShellError::labeled_error(
-                            format!("Could not load {}", cmd),
-                            "could not load command",
-                            document_tag,
-                        )
-                    })?,
-                    name.clone(),
-                );
-
-                short_desc.insert_untagged("name", cmd);
-                short_desc.insert_untagged(
-                    "description",
-                    get_data_by_key(&value, "usage".spanned_unknown())
-                        .ok_or_else(|| {
                             ShellError::labeled_error(
-                                "Expected a usage key",
+                                format!("Could not load {}", cmd),
-                                "expected a 'usage' key",
+                                "could not load command",
-                                &value.tag,
+                                document_tag,
                             )
-                        })?
+                        })?,
-                        .as_string()?,
+                        name.clone(),
-                );
+                    );
 
-                help.push_back(ReturnSuccess::value(short_desc.into_value()));
+                    short_desc.insert_untagged("name", cmd);
+                    short_desc.insert_untagged(
+                        "description",
+                        get_data_by_key(&value, "usage".spanned_unknown())
+                            .ok_or_else(|| {
+                                ShellError::labeled_error(
+                                    "Expected a usage key",
+                                    "expected a 'usage' key",
+                                    &value.tag,
+                                )
+                            })?
+                            .as_string()?,
+                    );
+
+                    yield ReturnSuccess::value(short_desc.into_value());
+                }
+            } else if rest.len() == 2 {
+                // Check for a subcommand
+                let command_name = format!("{} {}", rest[0].item, rest[1].item);
+                if let Some(command) = registry.get_command(&command_name) {
+                    yield Ok(ReturnSuccess::Value(UntaggedValue::string(get_help(command.stream_command(), &registry)).into_value(Tag::unknown())));
+                }
+            } else if let Some(command) = registry.get_command(&document.item) {
+                yield Ok(ReturnSuccess::Value(UntaggedValue::string(get_help(command.stream_command(), &registry)).into_value(Tag::unknown())));
+            } else {
+                yield Err(ShellError::labeled_error(
+                    "Can't find command (use 'help commands' for full list)",
+                    "can't find command",
+                    document.tag.span,
+                ));
             }
-        } else if rest.len() == 2 {
-            // Check for a subcommand
-            let command_name = format!("{} {}", rest[0].item, rest[1].item);
-            if let Some(command) = registry.get_command(&command_name) {
-                return Ok(get_help(command.stream_command(), &registry).into());
-            }
-        } else if let Some(command) = registry.get_command(&document.item) {
-            return Ok(get_help(command.stream_command(), &registry).into());
         } else {
-            return Err(ShellError::labeled_error(
+            let msg = r#"Welcome to Nushell.
-                "Can't find command (use 'help commands' for full list)",
-                "can't find command",
-                document.tag.span,
-            ));
-        }
-        let help = futures::stream::iter(help);
-        Ok(help.to_output_stream())
-    } else {
-        let msg = r#"Welcome to Nushell.
 
 Here are some tips to help you get started.
   * help commands - list all available commands
@@ -122,22 +121,17 @@ Get the processes on your system actively using CPU:
 
 You can also learn more at https://www.nushell.sh/book/"#;
 
-        let output_stream = futures::stream::iter(vec![ReturnSuccess::value(
+            yield Ok(ReturnSuccess::Value(UntaggedValue::string(msg).into_value(Tag::unknown())));
-            UntaggedValue::string(msg).into_value(name),
+        }
-        )]);
+    };
 
-        Ok(output_stream.to_output_stream())
+    Ok(stream.to_output_stream())
-    }
 }
 
 #[allow(clippy::cognitive_complexity)]
-pub(crate) fn get_help(
+pub fn get_help(cmd: &dyn WholeStreamCommand, registry: &CommandRegistry) -> String {
-    cmd: &dyn WholeStreamCommand,
-    registry: &CommandRegistry,
-) -> impl Into<OutputStream> {
     let cmd_name = cmd.name();
     let signature = cmd.signature();
-    let mut help = VecDeque::new();
     let mut long_desc = String::new();
 
     long_desc.push_str(&cmd.usage());
@@ -188,8 +182,8 @@ pub(crate) fn get_help(
 
     if !signature.positional.is_empty() || signature.rest_positional.is_some() {
         long_desc.push_str("\nParameters:\n");
-        for positional in signature.positional {
+        for positional in &signature.positional {
-            match positional.0 {
+            match &positional.0 {
                 PositionalType::Mandatory(name, _m) => {
                     long_desc.push_str(&format!("  <{}> {}\n", name, positional.1));
                 }
@@ -199,77 +193,15 @@ pub(crate) fn get_help(
             }
         }
 
-        if let Some(rest_positional) = signature.rest_positional {
+        if let Some(rest_positional) = &signature.rest_positional {
             long_desc.push_str(&format!("  ...args: {}\n", rest_positional.1));
         }
     }
     if !signature.named.is_empty() {
-        long_desc.push_str("\nFlags:\n");
+        long_desc.push_str(&get_flags_section(&signature))
-        for (flag, ty) in signature.named {
-            let msg = match ty.0 {
-                NamedType::Switch(s) => {
-                    if let Some(c) = s {
-                        format!(
-                            "  -{}, --{}{} {}\n",
-                            c,
-                            flag,
-                            if !ty.1.is_empty() { ":" } else { "" },
-                            ty.1
-                        )
-                    } else {
-                        format!(
-                            "  --{}{} {}\n",
-                            flag,
-                            if !ty.1.is_empty() { ":" } else { "" },
-                            ty.1
-                        )
-                    }
-                }
-                NamedType::Mandatory(s, m) => {
-                    if let Some(c) = s {
-                        format!(
-                            "  -{}, --{} <{}> (required parameter){} {}\n",
-                            c,
-                            flag,
-                            m.display(),
-                            if !ty.1.is_empty() { ":" } else { "" },
-                            ty.1
-                        )
-                    } else {
-                        format!(
-                            "  --{} <{}> (required parameter){} {}\n",
-                            flag,
-                            m.display(),
-                            if !ty.1.is_empty() { ":" } else { "" },
-                            ty.1
-                        )
-                    }
-                }
-                NamedType::Optional(s, o) => {
-                    if let Some(c) = s {
-                        format!(
-                            "  -{}, --{} <{}>{} {}\n",
-                            c,
-                            flag,
-                            o.display(),
-                            if !ty.1.is_empty() { ":" } else { "" },
-                            ty.1
-                        )
-                    } else {
-                        format!(
-                            "  --{} <{}>{} {}\n",
-                            flag,
-                            o.display(),
-                            if !ty.1.is_empty() { ":" } else { "" },
-                            ty.1
-                        )
-                    }
-                }
-            };
-            long_desc.push_str(&msg);
-        }
     }
 
+    let palette = crate::shell::palette::DefaultPalette {};
     let examples = cmd.examples();
     if !examples.is_empty() {
         long_desc.push_str("\nExamples:");
@@ -279,14 +211,92 @@ pub(crate) fn get_help(
         long_desc.push_str("  ");
         long_desc.push_str(example.description);
         let colored_example =
-            crate::shell::helper::Painter::paint_string(example.example, registry);
+            crate::shell::helper::Painter::paint_string(example.example, registry, &palette);
         long_desc.push_str(&format!("\n  > {}\n", colored_example));
     }
 
     long_desc.push_str("\n");
 
-    help.push_back(ReturnSuccess::value(
+    long_desc
-        UntaggedValue::string(long_desc).into_value(Tag::from((0, cmd_name.len(), None))),
+}
-    ));
+
-    help
+fn get_flags_section(signature: &Signature) -> String {
+    let mut long_desc = String::new();
+    long_desc.push_str("\nFlags:\n");
+    for (flag, ty) in &signature.named {
+        let msg = match ty.0 {
+            NamedType::Switch(s) => {
+                if let Some(c) = s {
+                    format!(
+                        "  -{}, --{}{} {}\n",
+                        c,
+                        flag,
+                        if !ty.1.is_empty() { ":" } else { "" },
+                        ty.1
+                    )
+                } else {
+                    format!(
+                        "  --{}{} {}\n",
+                        flag,
+                        if !ty.1.is_empty() { ":" } else { "" },
+                        ty.1
+                    )
+                }
+            }
+            NamedType::Mandatory(s, m) => {
+                if let Some(c) = s {
+                    format!(
+                        "  -{}, --{} <{}> (required parameter){} {}\n",
+                        c,
+                        flag,
+                        m.display(),
+                        if !ty.1.is_empty() { ":" } else { "" },
+                        ty.1
+                    )
+                } else {
+                    format!(
+                        "  --{} <{}> (required parameter){} {}\n",
+                        flag,
+                        m.display(),
+                        if !ty.1.is_empty() { ":" } else { "" },
+                        ty.1
+                    )
+                }
+            }
+            NamedType::Optional(s, o) => {
+                if let Some(c) = s {
+                    format!(
+                        "  -{}, --{} <{}>{} {}\n",
+                        c,
+                        flag,
+                        o.display(),
+                        if !ty.1.is_empty() { ":" } else { "" },
+                        ty.1
+                    )
+                } else {
+                    format!(
+                        "  --{} <{}>{} {}\n",
+                        flag,
+                        o.display(),
+                        if !ty.1.is_empty() { ":" } else { "" },
+                        ty.1
+                    )
+                }
+            }
+        };
+        long_desc.push_str(&msg);
+    }
+    long_desc
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Help;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Help {})
+    }
 }

crates/nu-cli/src/commands/histogram.rs

@@ -17,6 +17,7 @@ pub struct HistogramArgs {
     rest: Vec<Tagged<String>>,
 }
 
+#[async_trait]
 impl WholeStreamCommand for Histogram {
     fn name(&self) -> &str {
         "histogram"
@@ -39,38 +40,44 @@ impl WholeStreamCommand for Histogram {
         "Creates a new table with a histogram based on the column name passed in."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, histogram)?.run()
+        histogram(args, registry)
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[
+        vec![
             Example {
                 description: "Get a histogram for the types of files",
                 example: "ls | histogram type",
+                result: None,
             },
             Example {
                 description:
                     "Get a histogram for the types of files, with frequency column named count",
                 example: "ls | histogram type count",
+                result: None,
             },
             Example {
                 description: "Get a histogram for a list of numbers",
-                example: "echo [1 2 3 1 2 3 1 1 1 1 3 2 1 1 3] | wrap | histogram Column",
+                example: "echo [1 2 3 1 1 1 2 2 1 1] | histogram",
+                result: None,
             },
         ]
     }
 }
 
 pub fn histogram(
-    HistogramArgs { column_name, rest }: HistogramArgs,
+    args: CommandArgs,
-    RunnableContext { input, name, .. }: RunnableContext,
+    registry: &CommandRegistry,
 ) -> Result<OutputStream, ShellError> {
+    let registry = registry.clone();
+    let name = args.call_info.name_tag.clone();
     let stream = async_stream! {
+        let (HistogramArgs { column_name, rest}, mut input) = args.process(&registry).await?;
         let values: Vec<Value> = input.collect().await;
 
         let Tagged { item: group_by, .. } = column_name.clone();
@@ -101,6 +108,32 @@ pub fn histogram(
 
                 let column = (*column_name).clone();
 
+                let count_column_name = "count".to_string();
+                let count_shell_error = ShellError::labeled_error("Unable to load group count", "unabled to load group count", &name);
+                let mut count_values: Vec<u64> = Vec::new();
+
+                for table_entry in reduced.table_entries() {
+                    match table_entry {
+                        Value {
+                            value: UntaggedValue::Table(list),
+                            ..
+                        } => {
+                            for i in list {
+                                if let Ok(count) = i.value.clone().into_value(&name).as_u64() {
+                                    count_values.push(count);
+                                } else {
+                                    yield Err(count_shell_error);
+                                    return;
+                                }
+                            }
+                        }
+                        _ => {
+                            yield Err(count_shell_error);
+                            return;
+                        }
+                    }
+                }
+
                 if let Value { value: UntaggedValue::Table(start), .. } = datasets.get(0).ok_or_else(|| ShellError::labeled_error("Unable to load dataset", "unabled to load dataset", &name))? {
                     for percentage in start.iter() {
 
@@ -108,6 +141,8 @@ pub fn histogram(
                         let value: Tagged<String> = group_labels.get(idx).ok_or_else(|| ShellError::labeled_error("Unable to load group labels", "unabled to load group labels", &name))?.clone();
                         fact.insert_value(&column, UntaggedValue::string(value.item).into_value(value.tag));
 
+                        fact.insert_untagged(&count_column_name, UntaggedValue::int(count_values[idx]));
+
                         if let Value { value: UntaggedValue::Primitive(Primitive::Int(ref num)), ref tag } = percentage.clone() {
                             let string = std::iter::repeat("*").take(num.to_i32().ok_or_else(|| ShellError::labeled_error("Expected a number", "expected a number", tag))? as usize).collect::<String>();
                             fact.insert_untagged(&frequency_column_name, UntaggedValue::string(string));
@@ -176,3 +211,15 @@ fn percentages(values: &Value, max: Value, tag: impl Into<Tag>) -> Result<Value,
 
     Ok(results)
 }
+
+#[cfg(test)]
+mod tests {
+    use super::Histogram;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Histogram {})
+    }
+}

crates/nu-cli/src/commands/history.rs

@@ -8,9 +8,7 @@ use std::io::{BufRead, BufReader};
 
 pub struct History;
 
-#[derive(Deserialize)]
+#[async_trait]
-pub struct HistoryArgs {}
-
 impl WholeStreamCommand for History {
     fn name(&self) -> &str {
         "history"
@@ -24,19 +22,17 @@ impl WholeStreamCommand for History {
         "Display command history."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, history)?.run()
+        history(args, registry)
     }
 }
 
-fn history(
+fn history(args: CommandArgs, _registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
-    _: HistoryArgs,
+    let tag = args.call_info.name_tag;
-    RunnableContext { name: tag, .. }: RunnableContext,
-) -> Result<OutputStream, ShellError> {
     let stream = async_stream! {
         let history_path = HistoryFile::path();
         let file = File::open(history_path);
@@ -53,3 +49,15 @@ fn history(
     };
     Ok(stream.to_output_stream())
 }
+
+#[cfg(test)]
+mod tests {
+    use super::History;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(History {})
+    }
+}

crates/nu-cli/src/commands/insert.rs

@@ -13,6 +13,7 @@ pub struct InsertArgs {
     value: Value,
 }
 
+#[async_trait]
 impl WholeStreamCommand for Insert {
     fn name(&self) -> &str {
         "insert"
@@ -36,42 +37,53 @@ impl WholeStreamCommand for Insert {
         "Insert a new column with a given value."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, insert)?.run()
+        insert(args, registry)
     }
 }
 
-fn insert(
+fn insert(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
-    InsertArgs { column, value }: InsertArgs,
+    let registry = registry.clone();
-    RunnableContext { input, .. }: RunnableContext,
-) -> Result<OutputStream, ShellError> {
-    let mut input = input;
 
     let stream = async_stream! {
-        match input.next().await {
+        let (InsertArgs { column, value }, mut input) = args.process(&registry).await?;
-            Some(obj @ Value {
+        while let Some(row) = input.next().await {
-                value: UntaggedValue::Row(_),
+            match row {
-                ..
+                Value {
-            }) => match obj.insert_data_at_column_path(&column, value.clone()) {
+                    value: UntaggedValue::Row(_),
-                Ok(v) => yield Ok(ReturnSuccess::Value(v)),
+                    ..
-                Err(err) => yield Err(err),
+                } => match row.insert_data_at_column_path(&column, value.clone()) {
-            },
+                    Ok(v) => yield Ok(ReturnSuccess::Value(v)),
+                    Err(err) => yield Err(err),
+                },
+
+                Value { tag, ..} => {
+                    yield Err(ShellError::labeled_error(
+                        "Unrecognized type in stream",
+                        "original value",
+                        tag,
+                    ));
+                }
 
-            Some(Value { tag, ..}) => {
-                yield Err(ShellError::labeled_error(
-                    "Unrecognized type in stream",
-                    "original value",
-                    tag,
-                ));
             }
-
-            None => {}
         };
 
     };
     Ok(stream.to_output_stream())
 }
+
+#[cfg(test)]
+mod tests {
+    use super::Insert;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Insert {})
+    }
+}

crates/nu-cli/src/commands/is_empty.rs

@@ -20,6 +20,7 @@ pub struct IsEmptyArgs {
     rest: Vec<Value>,
 }
 
+#[async_trait]
 impl WholeStreamCommand for IsEmpty {
     fn name(&self) -> &str {
         "empty?"
@@ -36,21 +37,20 @@ impl WholeStreamCommand for IsEmpty {
         "Checks emptiness. The last value is the replacement value for any empty column(s) given to check against the table."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, is_empty)?.run()
+        is_empty(args, registry)
     }
 }
 
-fn is_empty(
+fn is_empty(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
-    IsEmptyArgs { rest }: IsEmptyArgs,
+    let registry = registry.clone();
-    RunnableContext { input, .. }: RunnableContext,
+    let stream = async_stream! {
-) -> Result<OutputStream, ShellError> {
+        let (IsEmptyArgs { rest }, mut input) = args.process(&registry).await?;
-    Ok(input
+        while let Some(value) = input.next().await {
-        .map(move |value| {
             let value_tag = value.tag();
 
             let action = if rest.len() <= 2 {
@@ -85,7 +85,7 @@ fn is_empty(
             };
 
             match action {
-                IsEmptyFor::Value => Ok(ReturnSuccess::Value(
+                IsEmptyFor::Value => yield Ok(ReturnSuccess::Value(
                     UntaggedValue::boolean(value.is_empty()).into_value(value_tag),
                 )),
                 IsEmptyFor::RowWithFieldsAndFallback(fields, default) => {
@@ -93,7 +93,7 @@ fn is_empty(
 
                     for field in fields.iter() {
                         let val =
-                            out.get_data_by_column_path(&field, Box::new(move |(_, _, err)| err))?;
+                            crate::commands::get::get_column_path(&field, &out)?;
 
                         let emptiness_value = match out {
                             obj
@@ -125,11 +125,11 @@ fn is_empty(
                         out = emptiness_value?;
                     }
 
-                    Ok(ReturnSuccess::Value(out))
+                    yield Ok(ReturnSuccess::Value(out))
                 }
                 IsEmptyFor::RowWithField(field) => {
                     let val =
-                        value.get_data_by_column_path(&field, Box::new(move |(_, _, err)| err))?;
+                        crate::commands::get::get_column_path(&field, &value)?;
 
                     match &value {
                         obj
@@ -143,18 +143,18 @@ fn is_empty(
                                     &field,
                                     UntaggedValue::boolean(true).into_value(&value_tag),
                                 ) {
-                                    Some(v) => Ok(ReturnSuccess::Value(v)),
+                                    Some(v) => yield Ok(ReturnSuccess::Value(v)),
-                                    None => Err(ShellError::labeled_error(
+                                    None => yield Err(ShellError::labeled_error(
                                         "empty? could not find place to check emptiness",
                                         "column name",
                                         &field.tag,
                                     )),
                                 }
                             } else {
-                                Ok(ReturnSuccess::Value(value))
+                                yield Ok(ReturnSuccess::Value(value))
                             }
                         }
-                        _ => Err(ShellError::labeled_error(
+                        _ => yield Err(ShellError::labeled_error(
                             "Unrecognized type in stream",
                             "original value",
                             &value_tag,
@@ -163,7 +163,7 @@ fn is_empty(
                 }
                 IsEmptyFor::RowWithFieldAndFallback(field, default) => {
                     let val =
-                        value.get_data_by_column_path(&field, Box::new(move |(_, _, err)| err))?;
+                        crate::commands::get::get_column_path(&field, &value)?;
 
                     match &value {
                         obj
@@ -174,18 +174,18 @@ fn is_empty(
                         } => {
                             if val.is_empty() {
                                 match obj.replace_data_at_column_path(&field, default) {
-                                    Some(v) => Ok(ReturnSuccess::Value(v)),
+                                    Some(v) => yield Ok(ReturnSuccess::Value(v)),
-                                    None => Err(ShellError::labeled_error(
+                                    None => yield Err(ShellError::labeled_error(
                                         "empty? could not find place to check emptiness",
                                         "column name",
                                         &field.tag,
                                     )),
                                 }
                             } else {
-                                Ok(ReturnSuccess::Value(value))
+                                yield Ok(ReturnSuccess::Value(value))
                             }
                         }
-                        _ => Err(ShellError::labeled_error(
+                        _ => yield Err(ShellError::labeled_error(
                             "Unrecognized type in stream",
                             "original value",
                             &value_tag,
@@ -193,6 +193,19 @@ fn is_empty(
                     }
                 }
             }
-        })
+        }
-        .to_output_stream())
+    };
+    Ok(stream.to_output_stream())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::IsEmpty;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(IsEmpty {})
+    }
 }

crates/nu-cli/src/commands/keep.rs

@@ -2,7 +2,7 @@ use crate::commands::WholeStreamCommand;
 use crate::context::CommandRegistry;
 use crate::prelude::*;
 use nu_errors::ShellError;
-use nu_protocol::{Signature, SyntaxShape};
+use nu_protocol::{ReturnSuccess, Signature, SyntaxShape, UntaggedValue};
 use nu_source::Tagged;
 
 pub struct Keep;
@@ -12,6 +12,7 @@ pub struct KeepArgs {
     rows: Option<Tagged<usize>>,
 }
 
+#[async_trait]
 impl WholeStreamCommand for Keep {
     fn name(&self) -> &str {
         "keep"
@@ -29,34 +30,66 @@ impl WholeStreamCommand for Keep {
         "Keep the number of rows only"
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, keep)?.run()
+        keep(args, registry)
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[
+        vec![
             Example {
                 description: "Keep the first row",
-                example: "ls | keep",
+                example: "echo [1 2 3] | keep",
+                result: Some(vec![UntaggedValue::int(1).into()]),
             },
             Example {
                 description: "Keep the first four rows",
-                example: "ls | keep 4",
+                example: "echo [1 2 3 4 5] | keep 4",
+                result: Some(vec![
+                    UntaggedValue::int(1).into(),
+                    UntaggedValue::int(2).into(),
+                    UntaggedValue::int(3).into(),
+                    UntaggedValue::int(4).into(),
+                ]),
             },
         ]
     }
 }
 
-fn keep(KeepArgs { rows }: KeepArgs, context: RunnableContext) -> Result<OutputStream, ShellError> {
+fn keep(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
-    let rows_desired = if let Some(quantity) = rows {
+    let registry = registry.clone();
-        *quantity
+    let stream = async_stream! {
-    } else {
+        let (KeepArgs { rows }, mut input) = args.process(&registry).await?;
-        1
+        let mut rows_desired = if let Some(quantity) = rows {
+            *quantity
+        } else {
+            1
+        };
+
+        while let Some(input) = input.next().await {
+            if rows_desired > 0 {
+                yield ReturnSuccess::value(input);
+                rows_desired -= 1;
+            } else {
+                break;
+            }
+        }
     };
 
-    Ok(OutputStream::from_input(context.input.take(rows_desired)))
+    Ok(stream.to_output_stream())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Keep;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Keep {})
+    }
 }

crates/nu-cli/src/commands/keep_until.rs

@@ -3,10 +3,13 @@ use crate::evaluate::evaluate_baseline_expr;
 use crate::prelude::*;
 use log::trace;
 use nu_errors::ShellError;
-use nu_protocol::{hir::ClassifiedCommand, Signature, SyntaxShape, UntaggedValue, Value};
+use nu_protocol::{
+    hir::ClassifiedCommand, ReturnSuccess, Signature, SyntaxShape, UntaggedValue, Value,
+};
 
 pub struct KeepUntil;
 
+#[async_trait]
 impl WholeStreamCommand for KeepUntil {
     fn name(&self) -> &str {
         "keep-until"
@@ -26,73 +29,96 @@ impl WholeStreamCommand for KeepUntil {
         "Keeps rows until the condition matches."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
         let registry = registry.clone();
         let scope = args.call_info.scope.clone();
-        let call_info = args.evaluate_once(&registry)?;
+        let stream = async_stream! {
+            let mut call_info = args.evaluate_once(&registry).await?;
 
-        let block = call_info.args.expect_nth(0)?.clone();
+            let block = call_info.args.expect_nth(0)?.clone();
 
-        let condition = match block {
+            let condition = match block {
-            Value {
+                Value {
-                value: UntaggedValue::Block(block),
+                    value: UntaggedValue::Block(block),
-                tag,
+                    tag,
-            } => {
+                } => {
-                if block.block.len() != 1 {
+                    if block.block.len() != 1 {
-                    return Err(ShellError::labeled_error(
+                        yield Err(ShellError::labeled_error(
-                        "Expected a condition",
-                        "expected a condition",
-                        tag,
-                    ));
-                }
-                match block.block[0].list.get(0) {
-                    Some(item) => match item {
-                        ClassifiedCommand::Expr(expr) => expr.clone(),
-                        _ => {
-                            return Err(ShellError::labeled_error(
-                                "Expected a condition",
-                                "expected a condition",
-                                tag,
-                            ))
-                        }
-                    },
-                    None => {
-                        return Err(ShellError::labeled_error(
                             "Expected a condition",
                             "expected a condition",
                             tag,
                         ));
+                        return;
+                    }
+                    match block.block[0].list.get(0) {
+                        Some(item) => match item {
+                            ClassifiedCommand::Expr(expr) => expr.clone(),
+                            _ => {
+                                yield Err(ShellError::labeled_error(
+                                    "Expected a condition",
+                                    "expected a condition",
+                                    tag,
+                                ));
+                                return;
+                            }
+                        },
+                        None => {
+                            yield Err(ShellError::labeled_error(
+                                "Expected a condition",
+                                "expected a condition",
+                                tag,
+                            ));
+                            return;
+                        }
                     }
                 }
-            }
+                Value { tag, .. } => {
-            Value { tag, .. } => {
+                    yield Err(ShellError::labeled_error(
-                return Err(ShellError::labeled_error(
+                        "Expected a condition",
-                    "Expected a condition",
+                        "expected a condition",
-                    "expected a condition",
+                        tag,
-                    tag,
+                    ));
-                ));
+                    return;
+                }
+            };
+
+            while let Some(item) = call_info.input.next().await {
+                let condition = condition.clone();
+                trace!("ITEM = {:?}", item);
+                let result =
+                    evaluate_baseline_expr(&*condition, &registry, &item, &scope.vars, &scope.env)
+                        .await;
+                trace!("RESULT = {:?}", result);
+
+                let return_value = match result {
+                    Ok(ref v) if v.is_true() => false,
+                    _ => true,
+                };
+
+                if return_value {
+                    yield ReturnSuccess::value(item);
+                } else {
+                    break;
+                }
             }
         };
 
-        let objects = call_info.input.take_while(move |item| {
+        Ok(stream.to_output_stream())
-            let condition = condition.clone();
+    }
-            trace!("ITEM = {:?}", item);
+}
-            let result =
+
-                evaluate_baseline_expr(&*condition, &registry, &scope.clone().set_it(item.clone()));
+#[cfg(test)]
-            trace!("RESULT = {:?}", result);
+mod tests {
-
+    use super::KeepUntil;
-            let return_value = match result {
+
-                Ok(ref v) if v.is_true() => false,
+    #[test]
-                _ => true,
+    fn examples_work_as_expected() {
-            };
+        use crate::examples::test as test_examples;
-
+
-            futures::future::ready(return_value)
+        test_examples(KeepUntil {})
-        });
-
-        Ok(objects.from_input_stream())
     }
 }

crates/nu-cli/src/commands/keep_while.rs

@@ -3,10 +3,13 @@ use crate::evaluate::evaluate_baseline_expr;
 use crate::prelude::*;
 use log::trace;
 use nu_errors::ShellError;
-use nu_protocol::{hir::ClassifiedCommand, Signature, SyntaxShape, UntaggedValue, Value};
+use nu_protocol::{
+    hir::ClassifiedCommand, ReturnSuccess, Signature, SyntaxShape, UntaggedValue, Value,
+};
 
 pub struct KeepWhile;
 
+#[async_trait]
 impl WholeStreamCommand for KeepWhile {
     fn name(&self) -> &str {
         "keep-while"
@@ -26,73 +29,96 @@ impl WholeStreamCommand for KeepWhile {
         "Keeps rows while the condition matches."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
         let registry = registry.clone();
         let scope = args.call_info.scope.clone();
-        let call_info = args.evaluate_once(&registry)?;
+        let stream = async_stream! {
+            let mut call_info = args.evaluate_once(&registry).await?;
 
-        let block = call_info.args.expect_nth(0)?.clone();
+            let block = call_info.args.expect_nth(0)?.clone();
 
-        let condition = match block {
+            let condition = match block {
-            Value {
+                Value {
-                value: UntaggedValue::Block(block),
+                    value: UntaggedValue::Block(block),
-                tag,
+                    tag,
-            } => {
+                } => {
-                if block.block.len() != 1 {
+                    if block.block.len() != 1 {
-                    return Err(ShellError::labeled_error(
+                        yield Err(ShellError::labeled_error(
-                        "Expected a condition",
-                        "expected a condition",
-                        tag,
-                    ));
-                }
-                match block.block[0].list.get(0) {
-                    Some(item) => match item {
-                        ClassifiedCommand::Expr(expr) => expr.clone(),
-                        _ => {
-                            return Err(ShellError::labeled_error(
-                                "Expected a condition",
-                                "expected a condition",
-                                tag,
-                            ))
-                        }
-                    },
-                    None => {
-                        return Err(ShellError::labeled_error(
                             "Expected a condition",
                             "expected a condition",
                             tag,
                         ));
+                        return;
+                    }
+                    match block.block[0].list.get(0) {
+                        Some(item) => match item {
+                            ClassifiedCommand::Expr(expr) => expr.clone(),
+                            _ => {
+                                yield Err(ShellError::labeled_error(
+                                    "Expected a condition",
+                                    "expected a condition",
+                                    tag,
+                                ));
+                                return;
+                            }
+                        },
+                        None => {
+                            yield Err(ShellError::labeled_error(
+                                "Expected a condition",
+                                "expected a condition",
+                                tag,
+                            ));
+                            return;
+                        }
                     }
                 }
-            }
+                Value { tag, .. } => {
-            Value { tag, .. } => {
+                    yield Err(ShellError::labeled_error(
-                return Err(ShellError::labeled_error(
+                        "Expected a condition",
-                    "Expected a condition",
+                        "expected a condition",
-                    "expected a condition",
+                        tag,
-                    tag,
+                    ));
-                ));
+                    return;
+                }
+            };
+
+            while let Some(item) = call_info.input.next().await {
+                let condition = condition.clone();
+                trace!("ITEM = {:?}", item);
+                let result =
+                    evaluate_baseline_expr(&*condition, &registry, &item, &scope.vars, &scope.env)
+                        .await;
+                trace!("RESULT = {:?}", result);
+
+                let return_value = match result {
+                    Ok(ref v) if v.is_true() => true,
+                    _ => false,
+                };
+
+                if return_value {
+                    yield ReturnSuccess::value(item);
+                } else {
+                    break;
+                }
             }
         };
 
-        let objects = call_info.input.take_while(move |item| {
+        Ok(stream.to_output_stream())
-            let condition = condition.clone();
+    }
-            trace!("ITEM = {:?}", item);
+}
-            let result =
+
-                evaluate_baseline_expr(&*condition, &registry, &scope.clone().set_it(item.clone()));
+#[cfg(test)]
-            trace!("RESULT = {:?}", result);
+mod tests {
-
+    use super::KeepWhile;
-            let return_value = match result {
+
-                Ok(ref v) if v.is_true() => true,
+    #[test]
-                _ => false,
+    fn examples_work_as_expected() {
-            };
+        use crate::examples::test as test_examples;
-
+
-            futures::future::ready(return_value)
+        test_examples(KeepWhile {})
-        });
-
-        Ok(objects.from_input_stream())
     }
 }

crates/nu-cli/src/commands/kill.rs

@@ -2,7 +2,7 @@ use crate::commands::WholeStreamCommand;
 use crate::context::CommandRegistry;
 use crate::prelude::*;
 use nu_errors::ShellError;
-use nu_protocol::{Signature, SyntaxShape};
+use nu_protocol::{ReturnSuccess, Signature, SyntaxShape, UntaggedValue};
 use nu_source::Tagged;
 use std::process::{Command, Stdio};
 
@@ -16,6 +16,7 @@ pub struct KillArgs {
     pub quiet: Tagged<bool>,
 }
 
+#[async_trait]
 impl WholeStreamCommand for Kill {
     fn name(&self) -> &str {
         "kill"
@@ -37,77 +38,97 @@ impl WholeStreamCommand for Kill {
         "Kill a process using the process id."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, kill)?.run()
+        kill(args, registry)
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[
+        vec![
             Example {
                 description: "Kill the pid using the most memory",
                 example: "ps | sort-by mem | last | kill $it.pid",
+                result: None,
             },
             Example {
                 description: "Force kill a given pid",
                 example: "kill --force 12345",
+                result: None,
             },
         ]
     }
 }
 
-fn kill(
+fn kill(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
-    KillArgs {
+    let registry = registry.clone();
-        pid,
-        rest,
-        force,
-        quiet,
-    }: KillArgs,
-    _context: RunnableContext,
-) -> Result<OutputStream, ShellError> {
-    let mut cmd = if cfg!(windows) {
-        let mut cmd = Command::new("taskkill");
 
-        if *force {
+    let stream = async_stream! {
-            cmd.arg("/F");
+        let (KillArgs {
-        }
+            pid,
+            rest,
+            force,
+            quiet,
+        }, mut input) = args.process(&registry).await?;
+        let mut cmd = if cfg!(windows) {
+            let mut cmd = Command::new("taskkill");
 
-        cmd.arg("/PID");
+            if *force {
-        cmd.arg(pid.item().to_string());
+                cmd.arg("/F");
+            }
 
-        // each pid must written as `/PID 0` otherwise
-        // taskkill will act as `killall` unix command
-        for id in &rest {
             cmd.arg("/PID");
-            cmd.arg(id.item().to_string());
+            cmd.arg(pid.item().to_string());
+
+            // each pid must written as `/PID 0` otherwise
+            // taskkill will act as `killall` unix command
+            for id in &rest {
+                cmd.arg("/PID");
+                cmd.arg(id.item().to_string());
+            }
+
+            cmd
+        } else {
+            let mut cmd = Command::new("kill");
+
+            if *force {
+                cmd.arg("-9");
+            }
+
+            cmd.arg(pid.item().to_string());
+
+            cmd.args(rest.iter().map(move |id| id.item().to_string()));
+
+            cmd
+        };
+
+        // pipe everything to null
+        if *quiet {
+            cmd.stdin(Stdio::null())
+                .stdout(Stdio::null())
+                .stderr(Stdio::null());
         }
 
-        cmd
+        cmd.status().expect("failed to execute shell command");
-    } else {
-        let mut cmd = Command::new("kill");
 
-        if *force {
+        if false {
-            cmd.arg("-9");
+            yield ReturnSuccess::value(UntaggedValue::nothing().into_value(Tag::unknown()));
         }
-
-        cmd.arg(pid.item().to_string());
-
-        cmd.args(rest.iter().map(move |id| id.item().to_string()));
-
-        cmd
     };
 
-    // pipe everything to null
+    Ok(stream.to_output_stream())
-    if *quiet {
+}
-        cmd.stdin(Stdio::null())
+
-            .stdout(Stdio::null())
+#[cfg(test)]
-            .stderr(Stdio::null());
+mod tests {
-    }
+    use super::Kill;
-
+
-    cmd.status().expect("failed to execute shell command");
+    #[test]
-
+    fn examples_work_as_expected() {
-    Ok(OutputStream::empty())
+        use crate::examples::test as test_examples;
+
+        test_examples(Kill {})
+    }
 }

crates/nu-cli/src/commands/last.rs

@@ -2,7 +2,7 @@ use crate::commands::WholeStreamCommand;
 use crate::context::CommandRegistry;
 use crate::prelude::*;
 use nu_errors::ShellError;
-use nu_protocol::{ReturnSuccess, Signature, SyntaxShape, Value};
+use nu_protocol::{ReturnSuccess, Signature, SyntaxShape, UntaggedValue, Value};
 use nu_source::Tagged;
 
 pub struct Last;
@@ -12,6 +12,7 @@ pub struct LastArgs {
     rows: Option<Tagged<u64>>,
 }
 
+#[async_trait]
 impl WholeStreamCommand for Last {
     fn name(&self) -> &str {
         "last"
@@ -29,46 +30,68 @@ impl WholeStreamCommand for Last {
         "Show only the last number of rows."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, last)?.run()
+        last(args, registry).await
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[
+        vec![
             Example {
                 description: "Get the last row",
-                example: "ls | last",
+                example: "echo [1 2 3] | last",
+                result: Some(vec![Value::from(UntaggedValue::from(BigInt::from(3)))]),
             },
             Example {
                 description: "Get the last three rows",
-                example: "ls | last 3",
+                example: "echo [1 2 3 4 5] | last 3",
+                result: Some(vec![
+                    UntaggedValue::int(3).into(),
+                    UntaggedValue::int(4).into(),
+                    UntaggedValue::int(5).into(),
+                ]),
             },
         ]
     }
 }
 
-fn last(LastArgs { rows }: LastArgs, context: RunnableContext) -> Result<OutputStream, ShellError> {
+async fn last(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
-    let stream = async_stream! {
+    let registry = registry.clone();
-        let v: Vec<_> = context.input.into_vec().await;
+    let (LastArgs { rows }, input) = args.process(&registry).await?;
+    let v: Vec<_> = input.into_vec().await;
 
-        let rows_desired = if let Some(quantity) = rows {
+    let rows_desired = if let Some(quantity) = rows {
-            *quantity
+        *quantity
-        } else {
+    } else {
-         1
+        1
-        };
-
-        let count = (rows_desired as usize);
-        if count < v.len() {
-            let k = v.len() - count;
-            for x in v[k..].iter() {
-                let y: Value = x.clone();
-                yield ReturnSuccess::value(y)
-            }
-        }
     };
-    Ok(stream.to_output_stream())
+
+    let mut values_vec_deque = VecDeque::new();
+
+    let count = rows_desired as usize;
+
+    if count < v.len() {
+        let k = v.len() - count;
+
+        for x in v[k..].iter() {
+            values_vec_deque.push_back(ReturnSuccess::value(x.clone()));
+        }
+    }
+
+    Ok(futures::stream::iter(values_vec_deque).to_output_stream())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Last;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Last {})
+    }
 }

crates/nu-cli/src/commands/lines.rs

@@ -5,6 +5,7 @@ use nu_protocol::{Primitive, ReturnSuccess, Signature, UntaggedValue, Value};
 
 pub struct Lines;
 
+#[async_trait]
 impl WholeStreamCommand for Lines {
     fn name(&self) -> &str {
         "lines"
@@ -18,7 +19,7 @@ impl WholeStreamCommand for Lines {
         "Split single string into rows, one per line."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
@@ -26,10 +27,11 @@ impl WholeStreamCommand for Lines {
         lines(args, registry)
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[Example {
+        vec![Example {
-            description: "Split output from an external command into lines",
+            description: "Split multi-line string into lines",
-            example: "^ls -l | lines",
+            example: r#"^echo "two\nlines" | lines"#,
+            result: None,
         }]
     }
 }
@@ -45,14 +47,14 @@ fn ends_with_line_ending(st: &str) -> bool {
 }
 
 fn lines(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
-    let args = args.evaluate_once(registry)?;
-    let tag = args.name_tag();
-    let name_span = tag.span;
-    let mut input = args.input;
-
     let mut leftover = vec![];
     let mut leftover_string = String::new();
+    let registry = registry.clone();
     let stream = async_stream! {
+        let args = args.evaluate_once(&registry).await.unwrap();
+        let tag = args.name_tag();
+        let name_span = tag.span;
+        let mut input = args.input;
         loop {
             match input.next().await {
                 Some(Value { value: UntaggedValue::Primitive(Primitive::String(st)), ..}) => {
@@ -72,6 +74,7 @@ fn lines(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream,
                     }
 
                     let success_lines: Vec<_> = lines.iter().map(|x| ReturnSuccess::value(UntaggedValue::line(x).into_untagged_value())).collect();
+
                     yield futures::stream::iter(success_lines)
                 }
                 Some(Value { value: UntaggedValue::Primitive(Primitive::Line(st)), ..}) => {
@@ -118,6 +121,17 @@ fn lines(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream,
         }
     }
     .flatten();
-
     Ok(stream.to_output_stream())
 }
+
+#[cfg(test)]
+mod tests {
+    use super::Lines;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Lines {})
+    }
+}

crates/nu-cli/src/commands/ls.rs

@@ -20,6 +20,7 @@ pub struct LsArgs {
     pub du: bool,
 }
 
+#[async_trait]
 impl WholeStreamCommand for Ls {
     fn name(&self) -> &str {
         "ls"
@@ -59,32 +60,47 @@ impl WholeStreamCommand for Ls {
         "View the contents of the current or given path."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, ls)?.run()
+        let name = args.call_info.name_tag.clone();
+        let ctrl_c = args.ctrl_c.clone();
+        let shell_manager = args.shell_manager.clone();
+        let (args, _) = args.process(&registry).await?;
+        shell_manager.ls(args, name, ctrl_c)
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[
+        vec![
             Example {
                 description: "List all files in the current directory",
                 example: "ls",
+                result: None,
             },
             Example {
                 description: "List all files in a subdirectory",
                 example: "ls subdir",
+                result: None,
             },
             Example {
                 description: "List all rust files",
                 example: "ls *.rs",
+                result: None,
             },
         ]
     }
 }
 
-fn ls(args: LsArgs, context: RunnableContext) -> Result<OutputStream, ShellError> {
+#[cfg(test)]
-    context.shell_manager.ls(args, &context)
+mod tests {
+    use super::Ls;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Ls {})
+    }
 }

crates/nu-cli/src/commands/map_max_by.rs

@@ -14,6 +14,7 @@ pub struct MapMaxByArgs {
     column_name: Option<Tagged<String>>,
 }
 
+#[async_trait]
 impl WholeStreamCommand for MapMaxBy {
     fn name(&self) -> &str {
         "map-max-by"
@@ -32,43 +33,52 @@ impl WholeStreamCommand for MapMaxBy {
         "Creates a new table with the data from the tables rows maxed by the column given."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, map_max_by)?.run()
+        map_max_by(args, registry).await
     }
 }
 
-pub fn map_max_by(
+pub async fn map_max_by(
-    MapMaxByArgs { column_name }: MapMaxByArgs,
+    args: CommandArgs,
-    RunnableContext { input, name, .. }: RunnableContext,
+    registry: &CommandRegistry,
 ) -> Result<OutputStream, ShellError> {
-    let stream = async_stream! {
+    let registry = registry.clone();
-        let values: Vec<Value> = input.collect().await;
+    let name = args.call_info.name_tag.clone();
+    let (MapMaxByArgs { column_name }, mut input) = args.process(&registry).await?;
+    let values: Vec<Value> = input.collect().await;
 
-
+    if values.is_empty() {
-        if values.is_empty() {
+        Err(ShellError::labeled_error(
-            yield Err(ShellError::labeled_error(
+            "Expected table from pipeline",
-                    "Expected table from pipeline",
+            "requires a table input",
-                    "requires a table input",
+            name,
-                    name
+        ))
-                ))
+    } else {
+        let map_by_column = if let Some(column_to_map) = column_name {
+            Some(column_to_map.item().clone())
         } else {
+            None
+        };
 
-            let map_by_column = if let Some(column_to_map) = column_name {
+        match map_max(&values[0], map_by_column, name) {
-                Some(column_to_map.item().clone())
+            Ok(table_maxed) => Ok(OutputStream::one(ReturnSuccess::value(table_maxed))),
-            } else {
+            Err(err) => Err(err),
-                None
-            };
-
-            match map_max(&values[0], map_by_column, name) {
-                Ok(table_maxed) => yield ReturnSuccess::value(table_maxed),
-                Err(err) => yield Err(err)
-            }
         }
-    };
+    }
-
+}
-    Ok(stream.to_output_stream())
+
+#[cfg(test)]
+mod tests {
+    use super::MapMaxBy;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(MapMaxBy {})
+    }
 }

crates/nu-cli/src/commands/merge.rs

@@ -14,6 +14,7 @@ pub struct MergeArgs {
     block: Block,
 }
 
+#[async_trait]
 impl WholeStreamCommand for Merge {
     fn name(&self) -> &str {
         "merge"
@@ -31,39 +32,38 @@ impl WholeStreamCommand for Merge {
         "Merge a table."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        Ok(args.process_raw(registry, merge)?.run())
+        merge(args, registry)
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[Example {
+        vec![Example {
             description: "Merge a 1-based index column with some ls output",
             example: "ls | select name | keep 3 | merge { echo [1 2 3] | wrap index }",
+            result: None,
         }]
     }
 }
 
-fn merge(
+fn merge(raw_args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
-    merge_args: MergeArgs,
+    let registry = registry.clone();
-    context: RunnableContext,
-    raw_args: RawCommandArgs,
-) -> Result<OutputStream, ShellError> {
-    let block = merge_args.block;
-    let registry = context.registry.clone();
-    let mut input = context.input;
     let scope = raw_args.call_info.scope.clone();
-
-    let mut context = Context::from_raw(&raw_args, &registry);
-
     let stream = async_stream! {
+        let mut context = Context::from_raw(&raw_args, &registry);
+        let name_tag = raw_args.call_info.name_tag.clone();
+        let (merge_args, mut input): (MergeArgs, _) = raw_args.process(&registry).await?;
+        let block = merge_args.block;
+
         let table: Option<Vec<Value>> = match run_block(&block,
                 &mut context,
                 InputStream::empty(),
-                &scope).await {
+                &scope.it,
+                &scope.vars,
+                &scope.env).await {
             Ok(mut stream) => Some(stream.drain_vec().await),
             Err(err) => {
                 yield Err(err);
@@ -74,7 +74,7 @@ fn merge(
 
         let table = table.unwrap_or_else(|| vec![Value {
             value: UntaggedValue::row(IndexMap::default()),
-            tag: raw_args.call_info.name_tag,
+            tag: name_tag,
         }]);
 
         let mut idx = 0;
@@ -101,3 +101,15 @@ fn merge(
 
     Ok(stream.to_output_stream())
 }
+
+#[cfg(test)]
+mod tests {
+    use super::Merge;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Merge {})
+    }
+}

crates/nu-cli/src/commands/mkdir.rs

@@ -11,38 +11,60 @@ pub struct Mkdir;
 #[derive(Deserialize)]
 pub struct MkdirArgs {
     pub rest: Vec<Tagged<PathBuf>>,
+    #[serde(rename = "show-created-paths")]
+    pub show_created_paths: bool,
 }
 
+#[async_trait]
 impl WholeStreamCommand for Mkdir {
     fn name(&self) -> &str {
         "mkdir"
     }
 
     fn signature(&self) -> Signature {
-        Signature::build("mkdir").rest(SyntaxShape::Path, "the name(s) of the path(s) to create")
+        Signature::build("mkdir")
+            .rest(SyntaxShape::Path, "the name(s) of the path(s) to create")
+            .switch("show-created-paths", "show the path(s) created.", Some('s'))
     }
 
     fn usage(&self) -> &str {
         "Make directories, creates intermediary directories as required."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, mkdir)?.run()
+        mkdir(args, registry).await
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[Example {
+        vec![Example {
             description: "Make a directory named foo",
             example: "mkdir foo",
+            result: None,
         }]
     }
 }
 
-fn mkdir(args: MkdirArgs, context: RunnableContext) -> Result<OutputStream, ShellError> {
+async fn mkdir(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
-    let shell_manager = context.shell_manager.clone();
+    let registry = registry.clone();
-    shell_manager.mkdir(args, &context)
+    let name = args.call_info.name_tag.clone();
+    let shell_manager = args.shell_manager.clone();
+    let (args, _) = args.process(&registry).await?;
+
+    shell_manager.mkdir(args, name)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Mkdir;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Mkdir {})
+    }
 }

crates/nu-cli/src/commands/mv.rs

@@ -14,6 +14,7 @@ pub struct MoveArgs {
     pub dst: Tagged<PathBuf>,
 }
 
+#[async_trait]
 impl WholeStreamCommand for Move {
     fn name(&self) -> &str {
         "mv"
@@ -37,33 +38,59 @@ impl WholeStreamCommand for Move {
         "Move files or directories."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, mv)?.run()
+        mv(args, registry)
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[
+        vec![
             Example {
                 description: "Rename a file",
                 example: "mv before.txt after.txt",
+                result: None,
             },
             Example {
                 description: "Move a file into a directory",
                 example: "mv test.txt my/subdirectory",
+                result: None,
             },
             Example {
                 description: "Move many files into a directory",
                 example: "mv *.txt my/subdirectory",
+                result: None,
             },
         ]
     }
 }
 
-fn mv(args: MoveArgs, context: RunnableContext) -> Result<OutputStream, ShellError> {
+fn mv(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
-    let shell_manager = context.shell_manager.clone();
+    let registry = registry.clone();
-    shell_manager.mv(args, &context)
+    let stream = async_stream! {
+        let name = args.call_info.name_tag.clone();
+        let shell_manager = args.shell_manager.clone();
+        let (args, _) = args.process(&registry).await?;
+        let mut result = shell_manager.mv(args, name)?;
+
+        while let Some(item) = result.next().await {
+            yield item;
+        }
+    };
+
+    Ok(stream.to_output_stream())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Move;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Move {})
+    }
 }

crates/nu-cli/src/commands/next.rs

@@ -5,6 +5,7 @@ use nu_protocol::{CommandAction, ReturnSuccess, Signature};
 
 pub struct Next;
 
+#[async_trait]
 impl WholeStreamCommand for Next {
     fn name(&self) -> &str {
         "n"
@@ -18,7 +19,7 @@ impl WholeStreamCommand for Next {
         "Go to next shell."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
@@ -30,3 +31,15 @@ impl WholeStreamCommand for Next {
 fn next(_args: CommandArgs, _registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
     Ok(vec![Ok(ReturnSuccess::Action(CommandAction::NextShell))].into())
 }
+
+#[cfg(test)]
+mod tests {
+    use super::Next;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Next {})
+    }
+}

crates/nu-cli/src/commands/nth.rs

@@ -2,7 +2,7 @@ use crate::commands::WholeStreamCommand;
 use crate::context::CommandRegistry;
 use crate::prelude::*;
 use nu_errors::ShellError;
-use nu_protocol::{ReturnSuccess, Signature, SyntaxShape};
+use nu_protocol::{ReturnSuccess, Signature, SyntaxShape, Value};
 use nu_source::Tagged;
 
 #[derive(Deserialize)]
@@ -13,6 +13,7 @@ struct NthArgs {
 
 pub struct Nth;
 
+#[async_trait]
 impl WholeStreamCommand for Nth {
     fn name(&self) -> &str {
         "nth"
@@ -32,38 +33,37 @@ impl WholeStreamCommand for Nth {
         "Return only the selected rows"
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, nth)?.run()
+        nth(args, registry)
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[
+        vec![
             Example {
                 description: "Get the second row",
-                example: "echo [first second third] | get 1",
+                example: "echo [first second third] | nth 1",
+                result: Some(vec![Value::from("second")]),
             },
             Example {
                 description: "Get the first and third rows",
-                example: "echo [first second third] | get 0 2",
+                example: "echo [first second third] | nth 0 2",
+                result: Some(vec![Value::from("first"), Value::from("third")]),
             },
         ]
     }
 }
 
-fn nth(
+fn nth(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
-    NthArgs {
+    let registry = registry.clone();
-        row_number,
+    let stream = async_stream! {
-        rest: and_rows,
+        let (NthArgs { row_number, rest: and_rows}, input) = args.process(&registry).await?;
-    }: NthArgs,
+
-    RunnableContext { input, .. }: RunnableContext,
+        let mut inp = input.enumerate();
-) -> Result<OutputStream, ShellError> {
+        while let Some((idx, item)) = inp.next().await {
-    let stream = input
-        .enumerate()
-        .map(move |(idx, item)| {
             let row_number = vec![row_number.clone()];
 
             let row_numbers = vec![&row_number, &and_rows]
@@ -71,18 +71,26 @@ fn nth(
                 .flatten()
                 .collect::<Vec<&Tagged<u64>>>();
 
-            let mut result = VecDeque::new();
-
             if row_numbers
                 .iter()
                 .any(|requested| requested.item == idx as u64)
             {
-                result.push_back(ReturnSuccess::value(item));
+                yield ReturnSuccess::value(item);
             }
-
+        }
-            futures::stream::iter(result)
+    };
-        })
-        .flatten();
 
     Ok(stream.to_output_stream())
 }
+
+#[cfg(test)]
+mod tests {
+    use super::Nth;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Nth {})
+    }
+}

crates/nu-cli/src/commands/open.rs

@@ -13,6 +13,7 @@ pub struct OpenArgs {
     raw: Tagged<bool>,
 }
 
+#[async_trait]
 impl WholeStreamCommand for Open {
     fn name(&self) -> &str {
         "open"
@@ -36,50 +37,50 @@ impl WholeStreamCommand for Open {
         "Load a file into a cell, convert to table if possible (avoid by appending '--raw')"
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, open)?.run()
+        open(args, registry).await
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![Example {
+            description: "Opens \"users.csv\" and creates a table from the data",
+            example: "open users.csv",
+            result: None,
+        }]
     }
 }
 
-fn open(
+async fn open(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
-    OpenArgs { path, raw }: OpenArgs,
+    let cwd = PathBuf::from(args.shell_manager.path());
-    RunnableContext { shell_manager, .. }: RunnableContext,
-) -> Result<OutputStream, ShellError> {
-    let cwd = PathBuf::from(shell_manager.path());
     let full_path = cwd;
+    let registry = registry.clone();
 
-    let stream = async_stream! {
+    let (OpenArgs { path, raw }, _) = args.process(&registry).await?;
+    let result = fetch(&full_path, &path.item, path.tag.span).await;
 
-        let result = fetch(&full_path, &path.item, path.tag.span).await;
+    let (file_extension, contents, contents_tag) = result?;
 
-        if let Err(e) = result {
+    let file_extension = if raw.item {
-            yield Err(e);
+        None
-            return;
+    } else {
-        }
+        // If the extension could not be determined via mimetype, try to use the path
-        let (file_extension, contents, contents_tag) = result?;
+        // extension. Some file types do not declare their mimetypes (such as bson files).
-
+        file_extension.or_else(|| path.extension().map(|x| x.to_string_lossy().to_string()))
-        let file_extension = if raw.item {
-            None
-        } else {
-            // If the extension could not be determined via mimetype, try to use the path
-            // extension. Some file types do not declare their mimetypes (such as bson files).
-            file_extension.or(path.extension().map(|x| x.to_string_lossy().to_string()))
-        };
-
-        let tagged_contents = contents.into_value(&contents_tag);
-
-        if let Some(extension) = file_extension {
-            yield Ok(ReturnSuccess::Action(CommandAction::AutoConvert(tagged_contents, extension)))
-        } else {
-            yield ReturnSuccess::value(tagged_contents);
-        }
     };
 
-    Ok(stream.to_output_stream())
+    let tagged_contents = contents.into_value(&contents_tag);
+
+    if let Some(extension) = file_extension {
+        Ok(OutputStream::one(ReturnSuccess::action(
+            CommandAction::AutoConvert(tagged_contents, extension),
+        )))
+    } else {
+        Ok(OutputStream::one(ReturnSuccess::value(tagged_contents)))
+    }
 }
 
 pub async fn fetch(
@@ -244,3 +245,15 @@ fn read_be_u16(input: &[u8]) -> Option<Vec<u16>> {
         Some(result)
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::Open;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Open {})
+    }
+}

crates/nu-cli/src/commands/parse.rs

@@ -1,167 +0,0 @@
-use crate::commands::WholeStreamCommand;
-use crate::context::CommandRegistry;
-use crate::prelude::*;
-use nu_errors::ShellError;
-use nu_protocol::{ReturnSuccess, Signature, SyntaxShape, TaggedDictBuilder, UntaggedValue};
-use nu_source::Tagged;
-use regex::Regex;
-
-#[derive(Debug)]
-enum ParseCommand {
-    Text(String),
-    Column(String),
-}
-
-fn parse(input: &str) -> Vec<ParseCommand> {
-    let mut output = vec![];
-
-    //let mut loop_input = input;
-    let mut loop_input = input.chars();
-    loop {
-        let mut before = String::new();
-
-        while let Some(c) = loop_input.next() {
-            if c == '{' {
-                break;
-            }
-            before.push(c);
-        }
-
-        if !before.is_empty() {
-            output.push(ParseCommand::Text(before.to_string()));
-        }
-        // Look for column as we're now at one
-        let mut column = String::new();
-
-        while let Some(c) = loop_input.next() {
-            if c == '}' {
-                break;
-            }
-            column.push(c);
-        }
-
-        if !column.is_empty() {
-            output.push(ParseCommand::Column(column.to_string()));
-        }
-
-        if before.is_empty() && column.is_empty() {
-            break;
-        }
-    }
-
-    output
-}
-
-fn column_names(commands: &[ParseCommand]) -> Vec<String> {
-    let mut output = vec![];
-
-    for command in commands {
-        if let ParseCommand::Column(c) = command {
-            output.push(c.clone());
-        }
-    }
-
-    output
-}
-
-fn build_regex(commands: &[ParseCommand]) -> String {
-    let mut output = String::new();
-
-    for command in commands {
-        match command {
-            ParseCommand::Text(s) => {
-                output.push_str(&s.replace("(", "\\("));
-            }
-            ParseCommand::Column(_) => {
-                output.push_str("(.*)");
-            }
-        }
-    }
-
-    output
-}
-pub struct Parse;
-
-#[derive(Deserialize)]
-pub struct ParseArgs {
-    pattern: Tagged<String>,
-}
-
-impl WholeStreamCommand for Parse {
-    fn name(&self) -> &str {
-        "parse"
-    }
-
-    fn signature(&self) -> Signature {
-        Signature::build("parse").required(
-            "pattern",
-            SyntaxShape::String,
-            "the pattern to match. Eg) \"{foo}: {bar}\"",
-        )
-    }
-
-    fn usage(&self) -> &str {
-        "Parse columns from string data using a simple pattern."
-    }
-
-    fn run(
-        &self,
-        args: CommandArgs,
-        registry: &CommandRegistry,
-    ) -> Result<OutputStream, ShellError> {
-        args.process(registry, parse_command)?.run()
-    }
-
-    fn examples(&self) -> &[Example] {
-        &[Example {
-            description: "Parse values from a string into a table",
-            example: r#"echo "data: 123" | parse "{key}: {value}""#,
-        }]
-    }
-}
-
-fn parse_command(
-    ParseArgs { pattern }: ParseArgs,
-    RunnableContext { name, input, .. }: RunnableContext,
-) -> Result<OutputStream, ShellError> {
-    let parse_pattern = parse(&pattern.item);
-    let parse_regex = build_regex(&parse_pattern);
-    let column_names = column_names(&parse_pattern);
-    let name = name.span;
-    let regex = Regex::new(&parse_regex).map_err(|_| {
-        ShellError::labeled_error(
-            "Could not parse regex",
-            "could not parse regex",
-            &pattern.tag,
-        )
-    })?;
-
-    Ok(input
-        .map(move |value| {
-            if let Ok(s) = value.as_string() {
-                let mut output = vec![];
-                for cap in regex.captures_iter(&s) {
-                    let mut dict = TaggedDictBuilder::new(value.tag());
-                    for (idx, column_name) in column_names.iter().enumerate() {
-                        dict.insert_untagged(
-                            column_name,
-                            UntaggedValue::string(cap[idx + 1].to_string()),
-                        );
-                    }
-                    output.push(Ok(ReturnSuccess::Value(dict.into_value())));
-                }
-                output
-            } else {
-                vec![Err(ShellError::labeled_error_with_secondary(
-                    "Expected string input",
-                    "expected string input",
-                    name,
-                    "value originated here",
-                    value.tag,
-                ))]
-            }
-        })
-        .map(futures::stream::iter)
-        .flatten()
-        .to_output_stream())
-}

crates/nu-cli/src/commands/parse/command.rs

@@ -0,0 +1,175 @@
+use crate::commands::WholeStreamCommand;
+use crate::prelude::*;
+use nu_errors::ShellError;
+use nu_protocol::{Signature, SyntaxShape, TaggedDictBuilder, UntaggedValue, Value};
+use nu_source::Tagged;
+
+use regex::Regex;
+
+#[derive(Deserialize)]
+struct Arguments {
+    pattern: Tagged<String>,
+    regex: Tagged<bool>,
+}
+
+pub struct Command;
+
+#[async_trait]
+impl WholeStreamCommand for Command {
+    fn name(&self) -> &str {
+        "parse"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("parse")
+            .required(
+                "pattern",
+                SyntaxShape::String,
+                "the pattern to match. Eg) \"{foo}: {bar}\"",
+            )
+            .switch("regex", "use full regex syntax for patterns", Some('r'))
+    }
+
+    fn usage(&self) -> &str {
+        "Parse columns from string data using a simple pattern."
+    }
+
+    async fn run(
+        &self,
+        args: CommandArgs,
+        registry: &CommandRegistry,
+    ) -> Result<OutputStream, ShellError> {
+        operate(args, registry).await
+    }
+}
+
+pub async fn operate(
+    args: CommandArgs,
+    registry: &CommandRegistry,
+) -> Result<OutputStream, ShellError> {
+    let name_tag = args.call_info.name_tag.clone();
+    let (Arguments { regex, pattern }, mut input) = args.process(&registry).await?;
+
+    let regex_pattern = if let Tagged { item: true, tag } = regex {
+        Regex::new(&pattern.item)
+            .map_err(|_| ShellError::labeled_error("Invalid regex", "invalid regex", tag.span))?
+    } else {
+        let parse_regex = build_regex(&pattern.item, name_tag.clone())?;
+
+        Regex::new(&parse_regex).map_err(|_| {
+            ShellError::labeled_error("Invalid pattern", "invalid pattern", name_tag.span)
+        })?
+    };
+
+    let columns = column_names(&regex_pattern);
+    let mut parsed: VecDeque<Value> = VecDeque::new();
+
+    while let Some(v) = input.next().await {
+        match v.as_string() {
+            Ok(s) => {
+                let results = regex_pattern.captures_iter(&s);
+
+                for c in results {
+                    let mut dict = TaggedDictBuilder::new(&v.tag);
+
+                    for (column_name, cap) in columns.iter().zip(c.iter().skip(1)) {
+                        let cap_string = cap.map(|v| v.as_str()).unwrap_or("").to_string();
+                        dict.insert_untagged(column_name, UntaggedValue::string(cap_string));
+                    }
+
+                    parsed.push_back(dict.into_value());
+                }
+            }
+            Err(_) => {
+                return Err(ShellError::labeled_error_with_secondary(
+                    "Expected string input",
+                    "expected string input",
+                    &name_tag,
+                    "value originated here",
+                    v.tag,
+                ))
+            }
+        }
+    }
+
+    Ok(futures::stream::iter(parsed).to_output_stream())
+}
+
+fn build_regex(input: &str, tag: Tag) -> Result<String, ShellError> {
+    let mut output = "(?s)\\A".to_string();
+
+    //let mut loop_input = input;
+    let mut loop_input = input.chars().peekable();
+    loop {
+        let mut before = String::new();
+        while let Some(c) = loop_input.next() {
+            if c == '{' {
+                // If '{{', still creating a plaintext parse command, but just for a single '{' char
+                if loop_input.peek() == Some(&'{') {
+                    let _ = loop_input.next();
+                } else {
+                    break;
+                }
+            }
+            before.push(c);
+        }
+
+        if !before.is_empty() {
+            output.push_str(&regex::escape(&before));
+        }
+
+        // Look for column as we're now at one
+        let mut column = String::new();
+        while let Some(c) = loop_input.next() {
+            if c == '}' {
+                break;
+            }
+            column.push(c);
+
+            if loop_input.peek().is_none() {
+                return Err(ShellError::labeled_error(
+                    "Found opening `{` without an associated closing `}`",
+                    "invalid parse pattern",
+                    tag,
+                ));
+            }
+        }
+
+        if !column.is_empty() {
+            output.push_str("(?P<");
+            output.push_str(&column);
+            output.push_str(">.*?)");
+        }
+
+        if before.is_empty() && column.is_empty() {
+            break;
+        }
+    }
+
+    output.push_str("\\z");
+    Ok(output)
+}
+
+fn column_names(regex: &Regex) -> Vec<String> {
+    regex
+        .capture_names()
+        .enumerate()
+        .skip(1)
+        .map(|(i, name)| {
+            name.map(String::from)
+                .unwrap_or_else(|| format!("Capture{}", i))
+        })
+        .collect()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Command;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Command {})
+    }
+}

crates/nu-cli/src/commands/parse/mod.rs

@@ -0,0 +1,3 @@
+mod command;
+
+pub use command::Command as Parse;

crates/nu-cli/src/commands/pivot.rs

@@ -18,6 +18,7 @@ pub struct PivotArgs {
     ignore_titles: bool,
 }
 
+#[async_trait]
 impl WholeStreamCommand for Pivot {
     fn name(&self) -> &str {
         "pivot"
@@ -45,25 +46,28 @@ impl WholeStreamCommand for Pivot {
         "Pivots the table contents so rows become columns and columns become rows."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, pivot)?.run()
+        pivot(args, registry)
     }
 }
 
-pub fn pivot(args: PivotArgs, context: RunnableContext) -> Result<OutputStream, ShellError> {
+pub fn pivot(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
+    let registry = registry.clone();
+    let name = args.call_info.name_tag.clone();
     let stream = async_stream! {
-        let input = context.input.into_vec().await;
+        let (args, mut input): (PivotArgs, _) = args.process(&registry).await?;
+        let input = input.into_vec().await;
 
         let descs = merge_descriptors(&input);
 
         let mut headers: Vec<String> = vec![];
 
         if args.rest.len() > 0 && args.header_row {
-            yield Err(ShellError::labeled_error("Can not provide header names and use header row", "using header row", context.name));
+            yield Err(ShellError::labeled_error("Can not provide header names and use header row", "using header row", name));
             return;
         }
 
@@ -75,17 +79,17 @@ pub fn pivot(args: PivotArgs, context: RunnableContext) -> Result<OutputStream,
                             if let Ok(s) = x.as_string() {
                                 headers.push(s.to_string());
                             } else {
-                                yield Err(ShellError::labeled_error("Header row needs string headers", "used non-string headers", context.name));
+                                yield Err(ShellError::labeled_error("Header row needs string headers", "used non-string headers", name));
                                 return;
                             }
                         }
                         _ => {
-                            yield Err(ShellError::labeled_error("Header row is incomplete and can't be used", "using incomplete header row", context.name));
+                            yield Err(ShellError::labeled_error("Header row is incomplete and can't be used", "using incomplete header row", name));
                             return;
                         }
                     }
                 } else {
-                    yield Err(ShellError::labeled_error("Header row is incomplete and can't be used", "using incomplete header row", context.name));
+                    yield Err(ShellError::labeled_error("Header row is incomplete and can't be used", "using incomplete header row", name));
                     return;
                 }
             }
@@ -107,7 +111,7 @@ pub fn pivot(args: PivotArgs, context: RunnableContext) -> Result<OutputStream,
 
         for desc in descs {
             let mut column_num: usize = 0;
-            let mut dict = TaggedDictBuilder::new(&context.name);
+            let mut dict = TaggedDictBuilder::new(&name);
 
             if !args.ignore_titles && !args.header_row {
                 dict.insert_untagged(headers[column_num].clone(), UntaggedValue::string(desc.clone()));
@@ -134,3 +138,15 @@ pub fn pivot(args: PivotArgs, context: RunnableContext) -> Result<OutputStream,
 
     Ok(OutputStream::new(stream))
 }
+
+#[cfg(test)]
+mod tests {
+    use super::Pivot;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Pivot {})
+    }
+}

crates/nu-cli/src/commands/plugin.rs

@@ -3,7 +3,7 @@ use crate::prelude::*;
 use derive_new::new;
 use log::trace;
 use nu_errors::ShellError;
-use nu_protocol::{Primitive, ReturnSuccess, ReturnValue, Signature, UntaggedValue, Value};
+use nu_protocol::{ReturnSuccess, ReturnValue, Signature, UntaggedValue, Value};
 use serde::{self, Deserialize, Serialize};
 use std::io::prelude::*;
 use std::io::BufReader;
@@ -42,6 +42,7 @@ pub struct PluginCommand {
     config: Signature,
 }
 
+#[async_trait]
 impl WholeStreamCommand for PluginCommand {
     fn name(&self) -> &str {
         &self.name
@@ -55,7 +56,7 @@ impl WholeStreamCommand for PluginCommand {
         &self.config.usage
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
@@ -70,180 +71,80 @@ pub fn filter_plugin(
     registry: &CommandRegistry,
 ) -> Result<OutputStream, ShellError> {
     trace!("filter_plugin :: {}", path);
+    let registry = registry.clone();
 
-    let scope = &args
+    let scope = args.call_info.scope.clone();
-        .call_info
-        .scope
-        .clone()
-        .set_it(UntaggedValue::string("$it").into_untagged_value());
 
-    let args = args.evaluate_once_with_scope(registry, &scope)?;
+    let stream = async_stream! {
+        let mut args = args.evaluate_once_with_scope(&registry, &scope).await?;
 
-    let mut child = std::process::Command::new(path)
+        let mut child = std::process::Command::new(path)
-        .stdin(std::process::Stdio::piped())
+            .stdin(std::process::Stdio::piped())
-        .stdout(std::process::Stdio::piped())
+            .stdout(std::process::Stdio::piped())
-        .spawn()
+            .spawn()
-        .expect("Failed to spawn child process");
+            .expect("Failed to spawn child process");
 
-    let mut bos: VecDeque<Value> = VecDeque::new();
+        let call_info = args.call_info.clone();
-    bos.push_back(UntaggedValue::Primitive(Primitive::BeginningOfStream).into_untagged_value());
-    let bos = futures::stream::iter(bos);
 
-    let mut eos: VecDeque<Value> = VecDeque::new();
+        trace!("filtering :: {:?}", call_info);
-    eos.push_back(UntaggedValue::Primitive(Primitive::EndOfStream).into_untagged_value());
-    let eos = futures::stream::iter(eos);
 
-    let call_info = args.call_info.clone();
+        // Beginning of the stream
+        {
+            let stdin = child.stdin.as_mut().expect("Failed to open stdin");
+            let stdout = child.stdout.as_mut().expect("Failed to open stdout");
 
-    trace!("filtering :: {:?}", call_info);
+            let mut reader = BufReader::new(stdout);
 
-    let stream = bos
+            let request = JsonRpc::new("begin_filter", call_info.clone());
-        .chain(args.input)
+            let request_raw = serde_json::to_string(&request);
-        .chain(eos)
-        .map(move |v| match v {
-            Value {
-                value: UntaggedValue::Primitive(Primitive::BeginningOfStream),
-                ..
-            } => {
-                let stdin = child.stdin.as_mut().expect("Failed to open stdin");
-                let stdout = child.stdout.as_mut().expect("Failed to open stdout");
 
-                let mut reader = BufReader::new(stdout);
+            match request_raw {
-
+                Err(_) => {
-                let request = JsonRpc::new("begin_filter", call_info.clone());
+                    yield Err(ShellError::labeled_error(
-                let request_raw = serde_json::to_string(&request);
+                        "Could not load json from plugin",
-
+                        "could not load json from plugin",
-                match request_raw {
+                        &call_info.name_tag,
-                    Err(_) => {
+                    ));
-                        let mut result = VecDeque::new();
-                        result.push_back(Err(ShellError::labeled_error(
-                            "Could not load json from plugin",
-                            "could not load json from plugin",
-                            &call_info.name_tag,
-                        )));
-                        return result;
-                    }
-                    Ok(request_raw) => match stdin.write(format!("{}\n", request_raw).as_bytes()) {
-                        Ok(_) => {}
-                        Err(err) => {
-                            let mut result = VecDeque::new();
-                            result.push_back(Err(ShellError::unexpected(format!("{}", err))));
-                            return result;
-                        }
-                    },
                 }
-
+                Ok(request_raw) => match stdin.write(format!("{}\n", request_raw).as_bytes()) {
-                let mut input = String::new();
+                    Ok(_) => {}
-                match reader.read_line(&mut input) {
-                    Ok(_) => {
-                        let response = serde_json::from_str::<NuResult>(&input);
-                        match response {
-                            Ok(NuResult::response { params }) => match params {
-                                Ok(params) => params,
-                                Err(e) => {
-                                    let mut result = VecDeque::new();
-                                    result.push_back(ReturnValue::Err(e));
-                                    result
-                                }
-                            },
-                            Err(e) => {
-                                let mut result = VecDeque::new();
-                                result.push_back(Err(ShellError::untagged_runtime_error(format!(
-                                    "Error while processing begin_filter response: {:?} {}",
-                                    e, input
-                                ))));
-                                result
-                            }
-                        }
-                    }
-                    Err(e) => {
-                        let mut result = VecDeque::new();
-                        result.push_back(Err(ShellError::untagged_runtime_error(format!(
-                            "Error while reading begin_filter response: {:?}",
-                            e
-                        ))));
-                        result
-                    }
-                }
-            }
-            Value {
-                value: UntaggedValue::Primitive(Primitive::EndOfStream),
-                ..
-            } => {
-                let stdin = child.stdin.as_mut().expect("Failed to open stdin");
-                let stdout = child.stdout.as_mut().expect("Failed to open stdout");
-
-                let mut reader = BufReader::new(stdout);
-
-                let request: JsonRpc<std::vec::Vec<Value>> = JsonRpc::new("end_filter", vec![]);
-                let request_raw = match serde_json::to_string(&request) {
-                    Ok(req) => req,
                     Err(err) => {
-                        let mut result = VecDeque::new();
+                        yield Err(ShellError::unexpected(format!("{}", err)));
-                        result.push_back(Err(ShellError::unexpected(format!("{}", err))));
-                        return result;
                     }
-                };
+                },
+            }
 
-                let _ = stdin.write(format!("{}\n", request_raw).as_bytes()); // TODO: Handle error
+            let mut input = String::new();
-
+            match reader.read_line(&mut input) {
-                let mut input = String::new();
+                Ok(_) => {
-                let result = match reader.read_line(&mut input) {
+                    let response = serde_json::from_str::<NuResult>(&input);
-                    Ok(_) => {
+                    match response {
-                        let response = serde_json::from_str::<NuResult>(&input);
+                        Ok(NuResult::response { params }) => match params {
-                        match response {
+                            Ok(params) => for param in params { yield param },
-                            Ok(NuResult::response { params }) => match params {
-                                Ok(params) => {
-                                    let request: JsonRpc<std::vec::Vec<Value>> =
-                                        JsonRpc::new("quit", vec![]);
-                                    let request_raw = serde_json::to_string(&request);
-                                    match request_raw {
-                                        Ok(request_raw) => {
-                                            let _ = stdin.write(format!("{}\n", request_raw).as_bytes()); // TODO: Handle error
-                                        }
-                                        Err(e) => {
-                                            let mut result = VecDeque::new();
-                                            result.push_back(Err(ShellError::untagged_runtime_error(format!(
-                                                "Error while processing begin_filter response: {:?} {}",
-                                                e, input
-                                            ))));
-                                            return result;
-                                        }
-                                    }
-
-                                    params
-                                }
-                                Err(e) => {
-                                    let mut result = VecDeque::new();
-                                    result.push_back(ReturnValue::Err(e));
-                                    result
-                                }
-                            },
                             Err(e) => {
-                                let mut result = VecDeque::new();
+                                yield ReturnValue::Err(e);
-                                result.push_back(Err(ShellError::untagged_runtime_error(format!(
-                                    "Error while processing end_filter response: {:?} {}",
-                                    e, input
-                                ))));
-                                result
                             }
+                        },
+                        Err(e) => {
+                            yield Err(ShellError::untagged_runtime_error(format!(
+                                "Error while processing begin_filter response: {:?} {}",
+                                e, input
+                            )));
                         }
                     }
-                    Err(e) => {
+                }
-                        let mut result = VecDeque::new();
+                Err(e) => {
-                        result.push_back(Err(ShellError::untagged_runtime_error(format!(
+                    yield Err(ShellError::untagged_runtime_error(format!(
-                            "Error while reading end_filter: {:?}",
+                        "Error while reading begin_filter response: {:?}",
-                            e
+                        e
-                        ))));
+                    )));
-                        result
+                }
-                    }
-                };
-
-                let _ = child.wait();
-
-                result
             }
-            _ => {
+        }
+
+        // Stream contents
+        {
+            while let Some(v) = args.input.next().await {
                 let stdin = child.stdin.as_mut().expect("Failed to open stdin");
                 let stdout = child.stdout.as_mut().expect("Failed to open stdout");
 
@@ -256,12 +157,10 @@ pub fn filter_plugin(
                         let _ = stdin.write(format!("{}\n", request_raw).as_bytes()); // TODO: Handle error
                     }
                     Err(e) => {
-                        let mut result = VecDeque::new();
+                        yield Err(ShellError::untagged_runtime_error(format!(
-                        result.push_back(Err(ShellError::untagged_runtime_error(format!(
                             "Error while processing filter response: {:?}",
                             e
-                        ))));
+                        )));
-                        return result;
                     }
                 }
 
@@ -271,36 +170,110 @@ pub fn filter_plugin(
                         let response = serde_json::from_str::<NuResult>(&input);
                         match response {
                             Ok(NuResult::response { params }) => match params {
-                                Ok(params) => params,
+                                Ok(params) => for param in params { yield param },
                                 Err(e) => {
-                                    let mut result = VecDeque::new();
+                                    yield ReturnValue::Err(e);
-                                    result.push_back(ReturnValue::Err(e));
-                                    result
                                 }
                             },
                             Err(e) => {
-                                let mut result = VecDeque::new();
+                                yield Err(ShellError::untagged_runtime_error(format!(
-                                result.push_back(Err(ShellError::untagged_runtime_error(format!(
                                     "Error while processing filter response: {:?}\n== input ==\n{}",
                                     e, input
-                                ))));
+                                )));
-                                result
                             }
                         }
                     }
                     Err(e) => {
-                        let mut result = VecDeque::new();
+                        yield Err(ShellError::untagged_runtime_error(format!(
-                        result.push_back(Err(ShellError::untagged_runtime_error(format!(
                             "Error while reading filter response: {:?}",
                             e
-                        ))));
+                        )));
-                        result
                     }
                 }
+
             }
-        })
+        }
-        .map(futures::stream::iter) // convert to a stream
+
-        .flatten();
+        // post stream contents
+        {
+            let stdin = child.stdin.as_mut().expect("Failed to open stdin");
+            let stdout = child.stdout.as_mut().expect("Failed to open stdout");
+
+            let mut reader = BufReader::new(stdout);
+
+            let request: JsonRpc<std::vec::Vec<Value>> = JsonRpc::new("end_filter", vec![]);
+            let request_raw = serde_json::to_string(&request);
+
+            match request_raw {
+                Err(_) => {
+                    yield Err(ShellError::labeled_error(
+                        "Could not load json from plugin",
+                        "could not load json from plugin",
+                        &call_info.name_tag,
+                    ));
+                }
+                Ok(request_raw) => match stdin.write(format!("{}\n", request_raw).as_bytes()) {
+                    Ok(_) => {}
+                    Err(err) => {
+                        yield Err(ShellError::unexpected(format!("{}", err)));
+                    }
+                },
+            }
+
+            let mut input = String::new();
+            match reader.read_line(&mut input) {
+                Ok(_) => {
+                    let response = serde_json::from_str::<NuResult>(&input);
+                    match response {
+                        Ok(NuResult::response { params }) => match params {
+                            Ok(params) => for param in params { yield param },
+                            Err(e) => {
+                                yield ReturnValue::Err(e);
+                            }
+                        },
+                        Err(e) => {
+                            yield Err(ShellError::untagged_runtime_error(format!(
+                                "Error while processing end_filter response: {:?} {}",
+                                e, input
+                            )));
+                        }
+                    }
+                }
+                Err(e) => {
+                    yield Err(ShellError::untagged_runtime_error(format!(
+                        "Error while reading end_filter response: {:?}",
+                        e
+                    )));
+                }
+            }
+        }
+
+        // End of the stream
+        {
+            let stdin = child.stdin.as_mut().expect("Failed to open stdin");
+            let stdout = child.stdout.as_mut().expect("Failed to open stdout");
+
+            let mut reader = BufReader::new(stdout);
+
+            let request: JsonRpc<std::vec::Vec<Value>> = JsonRpc::new("quit", vec![]);
+            let request_raw = serde_json::to_string(&request);
+
+            match request_raw {
+                Ok(request_raw) => {
+                    let _ = stdin.write(format!("{}\n", request_raw).as_bytes()); // TODO: Handle error
+                }
+                Err(e) => {
+                    yield Err(ShellError::untagged_runtime_error(format!(
+                        "Error while processing quit response: {:?}",
+                        e
+                    )));
+                    return;
+                }
+            }
+        }
+
+        let _ = child.wait();
+    };
 
     Ok(stream.to_output_stream())
 }
@@ -312,6 +285,7 @@ pub struct PluginSink {
     config: Signature,
 }
 
+#[async_trait]
 impl WholeStreamCommand for PluginSink {
     fn name(&self) -> &str {
         &self.name
@@ -325,7 +299,7 @@ impl WholeStreamCommand for PluginSink {
         &self.config.usage
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
@@ -339,10 +313,11 @@ pub fn sink_plugin(
     args: CommandArgs,
     registry: &CommandRegistry,
 ) -> Result<OutputStream, ShellError> {
-    let args = args.evaluate_once(registry)?;
+    let registry = registry.clone();
-    let call_info = args.call_info.clone();
-
     let stream = async_stream! {
+        let args = args.evaluate_once(&registry).await?;
+        let call_info = args.call_info.clone();
+
         let input: Vec<Value> = args.input.collect().await;
 
         let request = JsonRpc::new("sink", (call_info.clone(), input));

crates/nu-cli/src/commands/prepend.rs

@@ -2,7 +2,7 @@ use crate::commands::WholeStreamCommand;
 use crate::context::CommandRegistry;
 use crate::prelude::*;
 use nu_errors::ShellError;
-use nu_protocol::{Signature, SyntaxShape, Value};
+use nu_protocol::{ReturnSuccess, Signature, SyntaxShape, UntaggedValue, Value};
 
 #[derive(Deserialize)]
 struct PrependArgs {
@@ -11,6 +11,7 @@ struct PrependArgs {
 
 pub struct Prepend;
 
+#[async_trait]
 impl WholeStreamCommand for Prepend {
     fn name(&self) -> &str {
         "prepend"
@@ -28,27 +29,51 @@ impl WholeStreamCommand for Prepend {
         "Prepend the given row to the front of the table"
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, prepend)?.run()
+        prepend(args, registry)
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[Example {
+        vec![Example {
             description: "Add something to the beginning of a list or table",
             example: "echo [2 3 4] | prepend 1",
+            result: Some(vec![
+                UntaggedValue::int(1).into(),
+                UntaggedValue::int(2).into(),
+                UntaggedValue::int(3).into(),
+                UntaggedValue::int(4).into(),
+            ]),
         }]
     }
 }
 
-fn prepend(
+fn prepend(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
-    PrependArgs { row }: PrependArgs,
+    let registry = registry.clone();
-    RunnableContext { input, .. }: RunnableContext,
-) -> Result<OutputStream, ShellError> {
-    let prepend = futures::stream::iter(vec![row]);
 
-    Ok(prepend.chain(input).to_output_stream())
+    let stream = async_stream! {
+        let (PrependArgs { row }, mut input) = args.process(&registry).await?;
+
+        yield ReturnSuccess::value(row);
+        while let Some(item) = input.next().await {
+            yield ReturnSuccess::value(item);
+        }
+    };
+
+    Ok(stream.to_output_stream())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Prepend;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Prepend {})
+    }
 }

crates/nu-cli/src/commands/prev.rs

@@ -6,6 +6,7 @@ use crate::commands::WholeStreamCommand;
 
 pub struct Previous;
 
+#[async_trait]
 impl WholeStreamCommand for Previous {
     fn name(&self) -> &str {
         "p"
@@ -19,7 +20,7 @@ impl WholeStreamCommand for Previous {
         "Go to previous shell."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
@@ -31,3 +32,15 @@ impl WholeStreamCommand for Previous {
 fn previous(_args: CommandArgs, _registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
     Ok(vec![Ok(ReturnSuccess::Action(CommandAction::PreviousShell))].into())
 }
+
+#[cfg(test)]
+mod tests {
+    use super::Previous;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Previous {})
+    }
+}

crates/nu-cli/src/commands/pwd.rs

@@ -5,6 +5,7 @@ use nu_protocol::Signature;
 
 pub struct Pwd;
 
+#[async_trait]
 impl WholeStreamCommand for Pwd {
     fn name(&self) -> &str {
         "pwd"
@@ -18,24 +19,42 @@ impl WholeStreamCommand for Pwd {
         "Output the current working directory."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        pwd(args, registry)
+        pwd(args, registry).await
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[Example {
+        vec![Example {
             description: "Print the current working directory",
             example: "pwd",
+            result: None,
         }]
     }
 }
 
-pub fn pwd(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
+pub async fn pwd(
+    args: CommandArgs,
+    registry: &CommandRegistry,
+) -> Result<OutputStream, ShellError> {
+    let registry = registry.clone();
     let shell_manager = args.shell_manager.clone();
-    let args = args.evaluate_once(registry)?;
+    let args = args.evaluate_once(&registry).await?;
+
     shell_manager.pwd(args)
 }
+
+#[cfg(test)]
+mod tests {
+    use super::Pwd;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Pwd {})
+    }
+}

crates/nu-cli/src/commands/range.rs

@@ -3,7 +3,7 @@ use crate::context::CommandRegistry;
 use crate::deserializer::NumericRange;
 use crate::prelude::*;
 use nu_errors::ShellError;
-use nu_protocol::{Signature, SyntaxShape};
+use nu_protocol::{ReturnSuccess, Signature, SyntaxShape};
 use nu_source::Tagged;
 
 #[derive(Deserialize)]
@@ -13,6 +13,7 @@ struct RangeArgs {
 
 pub struct Range;
 
+#[async_trait]
 impl WholeStreamCommand for Range {
     fn name(&self) -> &str {
         "range"
@@ -30,25 +31,43 @@ impl WholeStreamCommand for Range {
         "Return only the selected rows"
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, range)?.run()
+        range(args, registry)
     }
 }
 
-fn range(
+fn range(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
-    RangeArgs { area }: RangeArgs,
+    let registry = registry.clone();
-    RunnableContext { input, .. }: RunnableContext,
+    let stream = async_stream! {
-) -> Result<OutputStream, ShellError> {
+        let (RangeArgs { area }, mut input) = args.process(&registry).await?;
-    let range = area.item;
+        let range = area.item;
-    let (from, _) = range.from;
+        let (from, _) = range.from;
-    let (to, _) = range.to;
+        let (to, _) = range.to;
 
-    let from = *from as usize;
+        let from = *from as usize;
-    let to = *to as usize;
+        let to = *to as usize;
 
-    Ok(input.skip(from).take(to - from + 1).to_output_stream())
+        let mut inp = input.skip(from).take(to - from + 1);
+        while let Some(item) = inp.next().await {
+            yield ReturnSuccess::value(item);
+        }
+    };
+
+    Ok(stream.to_output_stream())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Range;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Range {})
+    }
 }

crates/nu-cli/src/commands/reduce_by.rs

@@ -13,6 +13,7 @@ pub struct ReduceByArgs {
     reduce_with: Option<Tagged<String>>,
 }
 
+#[async_trait]
 impl WholeStreamCommand for ReduceBy {
     fn name(&self) -> &str {
         "reduce-by"
@@ -31,42 +32,52 @@ impl WholeStreamCommand for ReduceBy {
         "Creates a new table with the data from the tables rows reduced by the command given."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, reduce_by)?.run()
+        reduce_by(args, registry).await
     }
 }
 
-pub fn reduce_by(
+pub async fn reduce_by(
-    ReduceByArgs { reduce_with }: ReduceByArgs,
+    args: CommandArgs,
-    RunnableContext { input, name, .. }: RunnableContext,
+    registry: &CommandRegistry,
 ) -> Result<OutputStream, ShellError> {
-    let stream = async_stream! {
+    let registry = registry.clone();
-        let values: Vec<Value> = input.collect().await;
+    let name = args.call_info.name_tag.clone();
+    let (ReduceByArgs { reduce_with }, mut input) = args.process(&registry).await?;
+    let values: Vec<Value> = input.collect().await;
 
-        if values.is_empty() {
+    if values.is_empty() {
-            yield Err(ShellError::labeled_error(
+        return Err(ShellError::labeled_error(
-                    "Expected table from pipeline",
+            "Expected table from pipeline",
-                    "requires a table input",
+            "requires a table input",
-                    name
+            name,
-                ))
+        ));
-        } else {
+    }
 
-            let reduce_with = if let Some(reducer) = reduce_with {
+    let reduce_with = if let Some(reducer) = reduce_with {
-                Some(reducer.item().clone())
+        Some(reducer.item().clone())
-            } else {
+    } else {
-                None
+        None
-            };
-
-            match reduce(&values[0], reduce_with, name) {
-                Ok(reduced) => yield ReturnSuccess::value(reduced),
-                Err(err) => yield Err(err)
-            }
-        }
     };
 
-    Ok(stream.to_output_stream())
+    match reduce(&values[0], reduce_with, name) {
+        Ok(reduced) => Ok(OutputStream::one(ReturnSuccess::value(reduced))),
+        Err(err) => Err(err),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::ReduceBy;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(ReduceBy {})
+    }
 }

crates/nu-cli/src/commands/reject.rs

@@ -2,7 +2,7 @@ use crate::commands::WholeStreamCommand;
 use crate::data::base::reject_fields;
 use crate::prelude::*;
 use nu_errors::ShellError;
-use nu_protocol::{Signature, SyntaxShape};
+use nu_protocol::{ReturnSuccess, Signature, SyntaxShape};
 use nu_source::Tagged;
 
 #[derive(Deserialize)]
@@ -12,6 +12,7 @@ pub struct RejectArgs {
 
 pub struct Reject;
 
+#[async_trait]
 impl WholeStreamCommand for Reject {
     fn name(&self) -> &str {
         "reject"
@@ -25,30 +26,55 @@ impl WholeStreamCommand for Reject {
         "Remove the given columns from the table."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, reject)?.run()
+        reject(args, registry)
+    }
+
+    fn examples(&self) -> Vec<Example> {
+        vec![Example {
+            description: "Lists the files in a directory without showing the modified column",
+            example: "ls | reject modified",
+            result: None,
+        }]
     }
 }
 
-fn reject(
+fn reject(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
-    RejectArgs { rest: fields }: RejectArgs,
+    let registry = registry.clone();
-    RunnableContext { input, name, .. }: RunnableContext,
+    let stream = async_stream! {
-) -> Result<OutputStream, ShellError> {
+        let name = args.call_info.name_tag.clone();
-    if fields.is_empty() {
+        let (RejectArgs { rest: fields }, mut input) = args.process(&registry).await?;
-        return Err(ShellError::labeled_error(
+        if fields.is_empty() {
-            "Reject requires fields",
+            yield Err(ShellError::labeled_error(
-            "needs parameter",
+                "Reject requires fields",
-            name,
+                "needs parameter",
-        ));
+                name,
-    }
+            ));
+            return;
+        }
 
-    let fields: Vec<_> = fields.iter().map(|f| f.item.clone()).collect();
+        let fields: Vec<_> = fields.iter().map(|f| f.item.clone()).collect();
 
-    let stream = input.map(move |item| reject_fields(&item, &fields, &item.tag));
+        while let Some(item) = input.next().await {
+            yield ReturnSuccess::value(reject_fields(&item, &fields, &item.tag));
+        }
+    };
 
-    Ok(stream.from_input_stream())
+    Ok(stream.to_output_stream())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Reject;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Reject {})
+    }
 }

crates/nu-cli/src/commands/rename.rs

@@ -13,6 +13,7 @@ pub struct Arguments {
     rest: Vec<Tagged<String>>,
 }
 
+#[async_trait]
 impl WholeStreamCommand for Rename {
     fn name(&self) -> &str {
         "rename"
@@ -32,41 +33,41 @@ impl WholeStreamCommand for Rename {
         "Creates a new table with columns renamed."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, rename)?.run()
+        rename(args, registry)
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[
+        vec![
             Example {
                 description: "Rename a column",
-                example: "ls | rename my_name",
+                example: r#"echo "{a: 1, b: 2, c: 3}" | from json | rename my_column"#,
+                result: None,
             },
             Example {
                 description: "Rename many columns",
-                example: "echo \"{a: 1, b: 2, c: 3}\" | from json | rename spam eggs cars",
+                example: r#"echo "{a: 1, b: 2, c: 3}" | from json | rename spam eggs cars"#,
+                result: None,
             },
         ]
     }
 }
 
-pub fn rename(
+pub fn rename(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
-    Arguments { column_name, rest }: Arguments,
+    let registry = registry.clone();
-    RunnableContext { input, name, .. }: RunnableContext,
+    let name = args.call_info.name_tag.clone();
-) -> Result<OutputStream, ShellError> {
+    let stream = async_stream! {
-    let mut new_column_names = vec![vec![column_name]];
+        let (Arguments { column_name, rest }, mut input) = args.process(&registry).await?;
-    new_column_names.push(rest);
+        let mut new_column_names = vec![vec![column_name]];
+        new_column_names.push(rest);
 
-    let new_column_names = new_column_names.into_iter().flatten().collect::<Vec<_>>();
+        let new_column_names = new_column_names.into_iter().flatten().collect::<Vec<_>>();
-
-    let stream = input
-        .map(move |item| {
-            let mut result = VecDeque::new();
 
+        while let Some(item) = input.next().await {
             if let Value {
                 value: UntaggedValue::Row(row),
                 tag,
@@ -86,21 +87,31 @@ pub fn rename(
 
                 let out = UntaggedValue::Row(renamed_row.into()).into_value(tag);
 
-                result.push_back(ReturnSuccess::value(out));
+                yield ReturnSuccess::value(out);
             } else {
-                result.push_back(ReturnSuccess::value(
+                yield ReturnSuccess::value(
                     UntaggedValue::Error(ShellError::labeled_error(
                         "no column names available",
                         "can't rename",
                         &name,
                     ))
                     .into_untagged_value(),
-                ));
+                );
             }
-
+        }
-            futures::stream::iter(result)
+    };
-        })
-        .flatten();
 
     Ok(stream.to_output_stream())
 }
+
+#[cfg(test)]
+mod tests {
+    use super::Rename;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Rename {})
+    }
+}

crates/nu-cli/src/commands/reverse.rs

@@ -2,10 +2,11 @@ use crate::commands::WholeStreamCommand;
 use crate::context::CommandRegistry;
 use crate::prelude::*;
 use nu_errors::ShellError;
-use nu_protocol::Signature;
+use nu_protocol::{ReturnSuccess, Signature, UntaggedValue};
 
 pub struct Reverse;
 
+#[async_trait]
 impl WholeStreamCommand for Reverse {
     fn name(&self) -> &str {
         "reverse"
@@ -19,7 +20,7 @@ impl WholeStreamCommand for Reverse {
         "Reverses the table."
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
@@ -27,24 +28,44 @@ impl WholeStreamCommand for Reverse {
         reverse(args, registry)
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[Example {
+        vec![Example {
-            description: "Sort files in descending file size",
+            description: "Sort list of numbers in descending file size",
-            example: "ls | sort-by size | reverse",
+            example: "echo [3 1 2 19 0] | reverse",
+            result: Some(vec![
+                UntaggedValue::int(0).into(),
+                UntaggedValue::int(19).into(),
+                UntaggedValue::int(2).into(),
+                UntaggedValue::int(1).into(),
+                UntaggedValue::int(3).into(),
+            ]),
         }]
     }
 }
 
 fn reverse(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
-    let args = args.evaluate_once(registry)?;
+    let registry = registry.clone();
-    let (input, _args) = args.parts();
+    let stream = async_stream! {
+        let args = args.evaluate_once(&registry).await?;
+        let (input, _args) = args.parts();
 
-    let input = input.collect::<Vec<_>>();
+        let input = input.collect::<Vec<_>>().await;
+        for output in input.into_iter().rev() {
+            yield ReturnSuccess::value(output);
+        }
+    };
 
-    let output = input.map(move |mut vec| {
+    Ok(stream.to_output_stream())
-        vec.reverse();
+}
-        futures::stream::iter(vec)
+
-    });
+#[cfg(test)]
-
+mod tests {
-    Ok(output.flatten_stream().from_input_stream())
+    use super::Reverse;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Reverse {})
+    }
 }

crates/nu-cli/src/commands/rm.rs

@@ -14,8 +14,11 @@ pub struct RemoveArgs {
     pub recursive: Tagged<bool>,
     #[allow(unused)]
     pub trash: Tagged<bool>,
+    #[allow(unused)]
+    pub permanent: Tagged<bool>,
 }
 
+#[async_trait]
 impl WholeStreamCommand for Remove {
     fn name(&self) -> &str {
         "rm"
@@ -28,6 +31,11 @@ impl WholeStreamCommand for Remove {
                 "use the platform's recycle bin instead of permanently deleting",
                 Some('t'),
             )
+            .switch(
+                "permanent",
+                "don't use recycle bin, delete permanently",
+                Some('p'),
+            )
             .switch("recursive", "delete subdirectories recursively", Some('r'))
             .rest(SyntaxShape::Pattern, "the file path(s) to remove")
     }
@@ -36,29 +44,60 @@ impl WholeStreamCommand for Remove {
         "Remove file(s)"
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
     ) -> Result<OutputStream, ShellError> {
-        args.process(registry, rm)?.run()
+        rm(args, registry).await
     }
 
-    fn examples(&self) -> &[Example] {
+    fn examples(&self) -> Vec<Example> {
-        &[
+        vec![
             Example {
-                description: "Delete a file",
+                description: "Delete or move a file to the system trash (depending on 'rm_always_trash' config option)",
                 example: "rm file.txt",
+                result: None,
             },
             Example {
                 description: "Move a file to the system trash",
                 example: "rm --trash file.txt",
+                result: None,
+            },
+            Example {
+                description: "Delete a file permanently",
+                example: "rm --permanent file.txt",
+                result: None,
             },
         ]
     }
 }
 
-fn rm(args: RemoveArgs, context: RunnableContext) -> Result<OutputStream, ShellError> {
+async fn rm(args: CommandArgs, registry: &CommandRegistry) -> Result<OutputStream, ShellError> {
-    let shell_manager = context.shell_manager.clone();
+    let registry = registry.clone();
-    shell_manager.rm(args, &context)
+    let name = args.call_info.name_tag.clone();
+    let shell_manager = args.shell_manager.clone();
+    let (args, _): (RemoveArgs, _) = args.process(&registry).await?;
+
+    if args.trash.item && args.permanent.item {
+        return Ok(OutputStream::one(Err(ShellError::labeled_error(
+            "only one of --permanent and --trash can be used",
+            "conflicting flags",
+            name,
+        ))));
+    }
+
+    shell_manager.rm(args, name)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Remove;
+
+    #[test]
+    fn examples_work_as_expected() {
+        use crate::examples::test as test_examples;
+
+        test_examples(Remove {})
+    }
 }

crates/nu-cli/src/commands/run_alias.rs

@@ -13,6 +13,7 @@ pub struct AliasCommand {
     block: Block,
 }
 
+#[async_trait]
 impl WholeStreamCommand for AliasCommand {
     fn name(&self) -> &str {
         &self.name
@@ -32,7 +33,7 @@ impl WholeStreamCommand for AliasCommand {
         ""
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
@@ -47,10 +48,10 @@ impl WholeStreamCommand for AliasCommand {
 
         let stream = async_stream! {
             let mut scope = call_info.scope.clone();
-            let evaluated = call_info.evaluate(&registry)?;
+            let evaluated = call_info.evaluate(&registry).await?;
             if let Some(positional) = &evaluated.args.positional {
                 for (pos, arg) in positional.iter().enumerate() {
-                    scope = scope.set_var(alias_command.args[pos].to_string(), arg.clone());
+                    scope.vars.insert(alias_command.args[pos].to_string(), arg.clone());
                 }
             }
 
@@ -58,7 +59,9 @@ impl WholeStreamCommand for AliasCommand {
                 &block,
                 &mut context,
                 input,
-                &scope,
+                &scope.it,
+                &scope.vars,
+                &scope.env,
             ).await;
 
             match result {

crates/nu-cli/src/commands/run_external.rs

@@ -37,6 +37,7 @@ fn spanned_expression_to_string(expr: SpannedExpression) -> Result<String, Shell
     }
 }
 
+#[async_trait]
 impl WholeStreamCommand for RunExternalCommand {
     fn name(&self) -> &str {
         "run_external"
@@ -50,7 +51,7 @@ impl WholeStreamCommand for RunExternalCommand {
         ""
     }
 
-    fn run(
+    async fn run(
         &self,
         args: CommandArgs,
         registry: &CommandRegistry,
@@ -80,6 +81,7 @@ impl WholeStreamCommand for RunExternalCommand {
                     windows_drives_previous_cwd: Arc::new(Mutex::new(
                         std::collections::HashMap::new(),
                     )),
+                    raw_input: String::default(),
                 }
             }
             #[cfg(not(windows))]
@@ -90,6 +92,7 @@ impl WholeStreamCommand for RunExternalCommand {
                     shell_manager: args.shell_manager.clone(),
                     ctrl_c: args.ctrl_c.clone(),
                     current_errors: Arc::new(Mutex::new(vec![])),
+                    raw_input: String::default(),
                 }
             }
         };
@@ -117,16 +120,7 @@ impl WholeStreamCommand for RunExternalCommand {
                         })
                     };
 
-                    let context = RunnableContext {
+                    let result = external_context.shell_manager.cd(cd_args, args.call_info.name_tag.clone());
-                        input: InputStream::empty(),
-                        shell_manager: external_context.shell_manager.clone(),
-                        host: external_context.host.clone(),
-                        ctrl_c: external_context.ctrl_c.clone(),
-                        registry: external_context.registry.clone(),
-                        name: args.call_info.name_tag.clone(),
-                    };
-
-                    let result = external_context.shell_manager.cd(cd_args, &context);
                     match result {
                         Ok(mut stream) => {
                             while let Some(value) = stream.next().await {