A new type of shell
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Antoine Stevan 2492165fcb
FEATURE: print example command results in the help (#8189)
Should close #8035.

> **Note**
> this is my first technical PR for `nushell`
> - i might very well miss things
> - i tried to be as complete as possible about the changes
> - please require further changes if i did something wrong, i'm open to
any remark 😌

# Description
this PR adds, when it is defined in the `examples` method of the
`Command` implementations, the output of the examples to the output of
the `help` command.

this PR
- only modifies `crates/nu-engine/src/documentation.rs` and the
`get_documentation` function
- defines a new `WD` constant to print a **W**hite **D**immed `...`
- a `match` statement at the end of the example loop to
- print a white dimmed `...` when the example is not set, i.e. set to
`None` in the `examples` method of the `Command` implementation of a
command
- pretty print the output of the associated example `Value` when it has
been defined

> **Warning**
> LIMITATIONS:
> - i use snippets from `crates/nu-protocol/src/pipeline_data.rs`
> - the table creation from `pub PipelineData::print`, i.e. the `let
decl_id = ...;` and `let table = ...;` in the change
> - the table item printing from `PipelineData::write_all_and_flush`,
i.e. the `for item in table { ... }`
>
> ADDRESSED:
> - ~~the formatting of the output is not perfect and has to be fully
left aligned with the first column for now~~ (fixed with
[`5abeefd558c34ba9bae15e2f183ff4625442921e`..`a62be1b5a2c730959da5dbc028bb91ffe5093f63`](5abeefd558c34ba9bae15e2f183ff4625442921e..a62be1b5a2c730959da5dbc028bb91ffe5093f63))
> - ~~i'm using `.unwrap()` on both the changes above, not sure how to
handle this for now~~ (fixed for now thanks to 49f1dc080)
> - ~~the tests and `clippy` checks do not pass for now, see below~~
(`clippy` now is happy with 49f1dc080 and the tests pass with
11666bc715)

# User-Facing Changes
the output of the `help <command>` command is now augmented with the
outputs of the examples, when they are defined.
- `with-env`
```bash
> help with-env
...
Examples:
  Set the MYENV environment variable
  > with-env [MYENV "my env value"] { $env.MYENV }
  my env value

  Set by primitive value list
  > with-env [X Y W Z] { $env.X }
  Y

  Set by single row table
  > with-env [[X W]; [Y Z]] { $env.W }
  Z

  Set by key-value record
  > with-env {X: "Y", W: "Z"} { [$env.X $env.W] }
  ╭───┬───╮
  │ 0 │ Y │
  │ 1 │ Z │
  ╰───┴───╯
```
instead of the previous
```bash
> help with-env
...
Examples:
  Set the MYENV environment variable
  > with-env [MYENV "my env value"] { $env.MYENV }

  Set by primitive value list
  > with-env [X Y W Z] { $env.X }

  Set by single row table
  > with-env [[X W]; [Y Z]] { $env.W }

  Set by key-value record
  > with-env {X: "Y", W: "Z"} { [$env.X $env.W] }
```
- `merge`
```bash
> help merge
...
Examples:
  Add an 'index' column to the input table
  > [a b c] | wrap name | merge ( [1 2 3] | wrap index )
  ╭───┬──────╮
  │ # │ name │
  ├───┼──────┤
  │ 1 │ a    │
  │ 2 │ b    │
  │ 3 │ c    │
  ╰───┴──────╯

  Merge two records
  > {a: 1, b: 2} | merge {c: 3}
  ╭───┬───╮
  │ a │ 1 │
  │ b │ 2 │
  │ c │ 3 │
  ╰───┴───╯

  Merge two tables, overwriting overlapping columns
  > [{columnA: A0 columnB: B0}] | merge [{columnA: 'A0*'}]
  ╭───┬─────────┬─────────╮
  │ # │ columnA │ columnB │
  ├───┼─────────┼─────────┤
  │ 0 │ A0*     │ B0      │
  ╰───┴─────────┴─────────╯
```
instead of the previous
```bash
> help merge
...
Examples:
  Add an 'index' column to the input table
  > [a b c] | wrap name | merge ( [1 2 3] | wrap index )

  Merge two records
  > {a: 1, b: 2} | merge {c: 3}

  Merge two tables, overwriting overlapping columns
  > [{columnA: A0 columnB: B0}] | merge [{columnA: 'A0*'}]
```
2023-02-26 21:05:11 +01:00
.cargo reset stack size to 10mb vs 2gb (#7103) 2022-11-11 15:22:26 -06:00
.github Try to test similar things in coverage (#8056) 2023-02-25 17:04:42 +01:00
assets Add Windows Terminal profile and icon in Windows control panel (#5812) 2022-06-16 09:46:33 -07:00
benches Fix code in benchmarks (#7949) 2023-02-02 23:07:35 +01:00
crates FEATURE: print example command results in the help (#8189) 2023-02-26 21:05:11 +01:00
docker Add cross-rs config (#7559) 2022-12-22 08:52:07 -06:00
docs adds a config reset command (#6149) 2022-07-31 20:44:33 -05:00
images move items to showcase (#5569) 2022-05-17 18:21:14 -05:00
pkg_mgrs/winget added pkg_mgr/winget + yaml (#2297) 2020-08-11 05:45:53 +12:00
src FEATURE: print example command results in the help (#8189) 2023-02-26 21:05:11 +01:00
tests remove links to ShellError and ParseError docs - #8167 (#8193) 2023-02-24 09:26:31 -08:00
wix fix some typos (#7773) 2023-01-16 12:43:46 +01:00
.gitignore chore: add a couple of direnv specific files to the gitignore (#8165) 2023-02-22 12:58:06 +00:00
.typos.toml Add Github Actions workflow to check for typos (#7892) 2023-01-29 10:22:56 +13:00
build-all-maclin.sh Clean up .sh scripts with shellcheck (#7261) 2022-11-27 22:13:06 -05:00
build-all-windows.cmd Fix build-all-windows.cmd (#7674) 2023-01-03 18:31:36 -08:00
build-all.nu Move some from xxx commands to plugin (#7942) 2023-02-13 12:42:08 +00:00
build.rs Change embed-resource dep to slimmer winres (#5630) 2022-05-24 23:28:10 -04:00
Cargo.lock Cratification: Break out nu_cmd_lang into a separate crate (#8181) 2023-02-24 09:54:42 -06:00
Cargo.toml Cratification: Break out nu_cmd_lang into a separate crate (#8181) 2023-02-24 09:54:42 -06:00
CODE_OF_CONDUCT.md First pass at updating all documentation formatting and cleaning up output of examples (#2031) 2020-06-24 06:21:47 +12:00
codecov.yml Disable Windows coverage tracking for now (#8190) 2023-02-24 13:05:05 +01:00
CONTRIBUTING.md Feature cleanup (#7182) 2022-11-22 16:58:11 -08:00
coverage-local.nu update code coversage script to work better with windows (#8141) 2023-02-20 19:21:41 +00:00
coverage-local.sh Add a script to generate coverage locally (#8125) 2023-02-19 21:19:48 +00:00
Cross.toml Add cross-rs config (#7559) 2022-12-22 08:52:07 -06:00
install-all.ps1 Force install in install-all scripts (#8194) 2023-02-24 11:54:19 -06:00
install-all.sh Force install in install-all scripts (#8194) 2023-02-24 11:54:19 -06:00
LICENSE Include license text in all crates (#5094) 2022-04-08 10:47:13 +02:00
README.md Add links to the remaining README badges (#8191) 2023-02-24 12:58:44 +01:00
README.release.txt update text in readme file (#6557) 2022-09-14 15:25:55 +02:00
register-plugins.nu fix register-plugins script (#7677) 2023-01-04 11:22:54 -06:00
rust-toolchain.toml with the release of rust 1.67, let's bump to 1.66.1 (#7866) 2023-01-26 15:31:17 -06:00
uninstall-all.sh Move some from xxx commands to plugin (#7942) 2023-02-13 12:42:08 +00:00

Nushell

Crates.io Build Status Discord The Changelog #363 @nu_shell GitHub commit activity GitHub contributors codecov

A new type of shell.

Example of nushell

Table of Contents

Status

This project has reached a minimum-viable-product level of quality. Many people use it as their daily driver, but it may be unstable for some commands. Nu's design is subject to change as it matures.

Learning About Nu

The Nushell book is the primary source of Nushell documentation. You can find a full list of Nu commands in the book, and we have many examples of using Nu in our cookbook.

We're also active on Discord and Twitter; come and chat with us!

Installation

To quickly install Nu:

# Linux and macOS
brew install nushell
# Windows
winget install nushell

To use Nu in GitHub Action, check setup-nu for more detail.

Detailed installation instructions can be found in the installation chapter of the book. Nu is available via many package managers:

Packaging status

Philosophy

Nu draws inspiration from projects like PowerShell, functional programming languages, and modern CLI tools. Rather than thinking of files and data as raw streams of text, Nu looks at each input as something with structure. For example, when you list the contents of a directory what you get back is a table of rows, where each row represents an item in that directory. These values can be piped through a series of steps, in a series of commands called a 'pipeline'.

Pipelines

In Unix, it's common to pipe between commands to split up a sophisticated command over multiple steps. Nu takes this a step further and builds heavily on the idea of pipelines. As in the Unix philosophy, Nu allows commands to output to stdout and read from stdin. Additionally, commands can output structured data (you can think of this as a third kind of stream). Commands that work in the pipeline fit into one of three categories:

  • Commands that produce a stream (e.g., ls)
  • Commands that filter a stream (e.g., where type == "dir")
  • Commands that consume the output of the pipeline (e.g., table)

Commands are separated by the pipe symbol (|) to denote a pipeline flowing left to right.

> ls | where type == "dir" | table
╭────┬──────────┬──────┬─────────┬───────────────╮
│ #  │   name   │ type │  size   │   modified    │
├────┼──────────┼──────┼─────────┼───────────────┤
│  0 │ .cargo   │ dir  │     0 B │ 9 minutes ago │
│  1 │ assets   │ dir  │     0 B │ 2 weeks ago   │
│  2 │ crates   │ dir  │ 4.0 KiB │ 2 weeks ago   │
│  3 │ docker   │ dir  │     0 B │ 2 weeks ago   │
│  4 │ docs     │ dir  │     0 B │ 2 weeks ago   │
│  5 │ images   │ dir  │     0 B │ 2 weeks ago   │
│  6 │ pkg_mgrs │ dir  │     0 B │ 2 weeks ago   │
│  7 │ samples  │ dir  │     0 B │ 2 weeks ago   │
│  8 │ src      │ dir  │ 4.0 KiB │ 2 weeks ago   │
│  9 │ target   │ dir  │     0 B │ a day ago     │
│ 10 │ tests    │ dir  │ 4.0 KiB │ 2 weeks ago   │
│ 11 │ wix      │ dir  │     0 B │ 2 weeks ago   │
╰────┴──────────┴──────┴─────────┴───────────────╯

Because most of the time you'll want to see the output of a pipeline, table is assumed. We could have also written the above:

> ls | where type == "dir"

Being able to use the same commands and compose them differently is an important philosophy in Nu. For example, we could use the built-in ps command to get a list of the running processes, using the same where as above.

> ps | where cpu > 0
╭───┬───────┬───────────┬───────┬───────────┬───────────╮
│ # │  pid  │   name    │  cpu  │    mem    │  virtual  │
├───┼───────┼───────────┼───────┼───────────┼───────────┤
│ 02240 │ Slack.exe │ 16.40 │ 178.3 MiB │ 232.6 MiB │
│ 116948 │ Slack.exe │ 16.32 │ 205.0 MiB │ 197.9 MiB │
│ 217700 │ nu.exe    │  3.77 │  26.1 MiB │   8.8 MiB │
╰───┴───────┴───────────┴───────┴───────────┴───────────╯

Opening files

Nu can load file and URL contents as raw text or structured data (if it recognizes the format). For example, you can load a .toml file as structured data and explore it:

> open Cargo.toml
╭──────────────────┬────────────────────╮
│ bin              │ [table 1 row]      │
│ dependencies     │ {record 25 fields} │
│ dev-dependencies │ {record 8 fields}  │
│ features         │ {record 10 fields} │
│ package          │ {record 13 fields} │
│ patch            │ {record 1 field}   │
│ profile          │ {record 3 fields}  │
│ target           │ {record 3 fields}  │
│ workspace        │ {record 1 field}   │
╰──────────────────┴────────────────────╯

We can pipe this into a command that gets the contents of one of the columns:

> open Cargo.toml | get package
╭───────────────┬────────────────────────────────────╮
│ authors       │ [list 1 item]                      │
│ default-run   │ nu                                 │
│ description   │ A new type of shell                │
│ documentation │ https://www.nushell.sh/book/       │
│ edition       │ 2018                               │
│ exclude       │ [list 1 item]                      │
│ homepage      │ https://www.nushell.sh             │
│ license       │ MIT                                │
│ metadata      │ {record 1 field}                   │
│ name          │ nu                                 │
│ repository    │ https://github.com/nushell/nushell │
│ rust-version  │ 1.60                               │
│ version       │ 0.72.0                             │
╰───────────────┴────────────────────────────────────╯

And if needed we can drill down further:

> open Cargo.toml | get package.version
0.72.0

Plugins

Nu supports plugins that offer additional functionality to the shell and follow the same structured data model that built-in commands use. There are a few examples in the crates/nu_plugins_* directories.

Plugins are binaries that are available in your path and follow a nu_plugin_* naming convention. These binaries interact with nu via a simple JSON-RPC protocol where the command identifies itself and passes along its configuration, making it available for use. If the plugin is a filter, data streams to it one element at a time, and it can stream data back in return via stdin/stdout. If the plugin is a sink, it is given the full vector of final data and is given free reign over stdin/stdout to use as it pleases.

The awesome-nu repo lists a variety of nu-plugins.

Goals

Nu adheres closely to a set of goals that make up its design philosophy. As features are added, they are checked against these goals.

  • First and foremost, Nu is cross-platform. Commands and techniques should work across platforms and Nu has first-class support for Windows, macOS, and Linux.

  • Nu ensures compatibility with existing platform-specific executables.

  • Nu's workflow and tools should have the usability expected of modern software in 2022 (and beyond).

  • Nu views data as either structured or unstructured. It is a structured shell like PowerShell.

  • Finally, Nu views data functionally. Rather than using mutation, pipelines act as a means to load, change, and save data without mutable state.

Progress

Nu is under heavy development and will naturally change as it matures. The chart below isn't meant to be exhaustive, but it helps give an idea for some of the areas of development and their relative maturity:

Features Not started Prototype MVP Preview Mature Notes
Aliases X Aliases allow for shortening large commands, while passing flags
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 and scoped environment 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 updated to latest release, including usage examples
Paging X Textview has paging, but we'd like paging for tables
Functions X Functions and aliases are supported
Variables X Nu supports variables and environment variables
Completions X Completions for filepaths
Type-checking x Commands check basic types, and input/output types

Officially Supported By

Please submit an issue or PR to be added to this list.

Contributing

See Contributing for details. Thanks to all the people who already contributed!

License

The project is made available under the MIT license. See the LICENSE file for more information.