dd7b7311b3
# Description * I was dismayed to discover recently that UnsupportedInput and TypeMismatch are used *extremely* inconsistently across the codebase. UnsupportedInput is sometimes used for input type-checks (as per the name!!), but *also* used for argument type-checks. TypeMismatch is also used for both. I thus devised the following standard: input type-checking *only* uses UnsupportedInput, and argument type-checking *only* uses TypeMismatch. Moreover, to differentiate them, UnsupportedInput now has *two* error arrows (spans), one pointing at the command and the other at the input origin, while TypeMismatch only has the one (because the command should always be nearby) * In order to apply that standard, a very large number of UnsupportedInput uses were changed so that the input's span could be retrieved and delivered to it. * Additionally, I noticed many places where **errors are not propagated correctly**: there are lots of `match` sites which take a Value::Error, then throw it away and replace it with a new Value::Error with less/misleading information (such as reporting the error as an "incorrect type"). I believe that the earliest errors are the most important, and should always be propagated where possible. * Also, to standardise one broad subset of UnsupportedInput error messages, who all used slightly different wordings of "expected `<type>`, got `<type>`", I created OnlySupportsThisInputType as a variant of it. * Finally, a bunch of error sites that had "repeated spans" - i.e. where an error expected two spans, but `call.head` was given for both - were fixed to use different spans. # Example BEFORE ``` 〉20b | str starts-with 'a' Error: nu:🐚:unsupported_input (link) × Unsupported input ╭─[entry #31:1:1] 1 │ 20b | str starts-with 'a' · ┬ · ╰── Input's type is filesize. This command only works with strings. ╰──── 〉'a' | math cos Error: nu:🐚:unsupported_input (link) × Unsupported input ╭─[entry #33:1:1] 1 │ 'a' | math cos · ─┬─ · ╰── Only numerical values are supported, input type: String ╰──── 〉0x[12] | encode utf8 Error: nu:🐚:unsupported_input (link) × Unsupported input ╭─[entry #38:1:1] 1 │ 0x[12] | encode utf8 · ───┬── · ╰── non-string input ╰──── ``` AFTER ``` 〉20b | str starts-with 'a' Error: nu:🐚:pipeline_mismatch (link) × Pipeline mismatch. ╭─[entry #1:1:1] 1 │ 20b | str starts-with 'a' · ┬ ───────┬─────── · │ ╰── only string input data is supported · ╰── input type: filesize ╰──── 〉'a' | math cos Error: nu:🐚:pipeline_mismatch (link) × Pipeline mismatch. ╭─[entry #2:1:1] 1 │ 'a' | math cos · ─┬─ ────┬─── · │ ╰── only numeric input data is supported · ╰── input type: string ╰──── 〉0x[12] | encode utf8 Error: nu:🐚:pipeline_mismatch (link) × Pipeline mismatch. ╭─[entry #3:1:1] 1 │ 0x[12] | encode utf8 · ───┬── ───┬── · │ ╰── only string input data is supported · ╰── input type: binary ╰──── ``` # User-Facing Changes Various error messages suddenly make more sense (i.e. have two arrows instead of one). # Tests + Formatting Don't forget to add tests that cover your changes. Make sure you've run and fixed any issues with these commands: - `cargo fmt --all -- --check` to check standard code formatting (`cargo fmt --all` applies these changes) - `cargo clippy --workspace -- -D warnings -D clippy::unwrap_used -A clippy::needless_collect` to check that you're using the standard code style - `cargo test --workspace` to check that all tests pass # After Submitting If your PR had any user-facing changes, update [the documentation](https://github.com/nushell/nushell.github.io) after the PR is merged, if necessary. This will help us keep the docs up to date. |
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|---|---|---|
| .cargo | ||
| .github | ||
| assets | ||
| crates | ||
| docker | ||
| docs | ||
| images | ||
| pkg_mgrs/winget | ||
| src | ||
| tests | ||
| wix | ||
| .gitignore | ||
| build-all-maclin.sh | ||
| build-all-windows.cmd | ||
| build-all.nu | ||
| build.rs | ||
| Cargo.lock | ||
| Cargo.toml | ||
| CODE_OF_CONDUCT.md | ||
| CONTRIBUTING.md | ||
| Cross.toml | ||
| install-all.ps1 | ||
| install-all.sh | ||
| LICENSE | ||
| README.md | ||
| README.release.txt | ||
| register-plugins.nu | ||
| rust-toolchain.toml | ||
| uninstall-all.sh | ||
Nushell
A new type of shell.
Table of Contents
- Status
- Learning About Nu
- Installation
- Philosophy
- Goals
- Progress
- Officially Supported By
- Contributing
- License
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:
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 │
├───┼───────┼───────────┼───────┼───────────┼───────────┤
│ 0 │ 2240 │ Slack.exe │ 16.40 │ 178.3 MiB │ 232.6 MiB │
│ 1 │ 16948 │ Slack.exe │ 16.32 │ 205.0 MiB │ 197.9 MiB │
│ 2 │ 17700 │ 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.
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.