132ikl 13d5a15f75
Run-time pipeline input typechecking tweaks (#14922)
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# Description
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This PR makes two changes related to [run-time pipeline input type
checking](https://github.com/nushell/nushell/pull/14741):

1. The check which bypasses type checking for commands with only
`Type::Nothing` input types has been expanded to work with commands with
multiple `Type::Nothing` inputs for different outputs. For example,
`ast` has three input/output type pairs, but all of the inputs are
`Type::Nothing`:
  ```
  ╭───┬─────────┬────────╮
  │ # │  input  │ output │
  ├───┼─────────┼────────┤
  │ 0 │ nothing │ table  │
  │ 1 │ nothing │ record │
  │ 2 │ nothing │ string │
  ╰───┴─────────┴────────╯
  ```
Before this PR, passing a value (which would otherwise be ignored) to
`ast` caused a run-time type error:
  ```
    Error: nu:🐚:only_supports_this_input_type
  
    × Input type not supported.
     ╭─[entry #1:1:6]
   1 │ echo 123 | ast -j -f "hi" 
     ·      ─┬─   ─┬─
· │ ╰── only nothing, nothing, and nothing input data is supported
     ·       ╰── input type: int
     ╰────
  
  ```

  After this PR, no error is raised.

This doesn't really matter for `ast` (the only other built-in command
with a similar input/output type signature is `cal`), but it's more
logically consistent.

2. Bypasses input type-checking (parse-time ***and*** run-time) for some
(not all, see below) commands which have both a `Type::Nothing` input
and some other non-nothing `Type` input. This is accomplished by adding
a `Type::Any` input with the same output as the corresponding
`Type::Nothing` input/output pair.
  &nbsp;
This is necessary because some commands are intended to operate on an
argument with empty pipeline input, or operate on an empty pipeline
input with no argument. This causes issues when a value is implicitly
passed to one of these commands. I [discovered this
issue](https://discord.com/channels/601130461678272522/615962413203718156/1329945784346611712)
when working with an example where the `open` command is used in
`sort-by` closure:
```nushell
ls | sort-by { open -r $in.name | lines | length }
```

Before this PR (but after the run-time input type checking PR), this
error is raised:

```
Error: nu:🐚:only_supports_this_input_type

  × Input type not supported.
   ╭─[entry #1:1:1]
 1 │ ls | sort-by { open -r $in.name | lines | length }
   · ─┬             ──┬─
   ·  │               ╰── only nothing and string input data is supported
   ·  ╰── input type: record<name: string, type: string, size: filesize, modified: date>
   ╰────
```

While this error is technically correct, we don't actually want to
return an error here since `open` ignores its pipeline input when an
argument is passed. This would be a parse-time error as well if the
parser was able to infer that the closure input type was a record, but
our type inference isn't that robust currently, so this technically
incorrect form snuck by type checking until #14741.

However, there are some commands with the same kind of type signature
where this behavior is actually desirable. This means we can't just
bypass type-checking for any command with a `Type::Nothing` input. These
commands operate on true `null` values, rather than ignoring their
input. For example, `length` returns `0` when passed a `null` value.
It's correct, and even desirable, to throw a run-time error when
`length` is passed an unexpected type. For example, a string, which
should instead be measured with `str length`:

```nushell
["hello" "world"] | sort-by { length }
# => Error: nu:🐚:only_supports_this_input_type
# => 
# =>   × Input type not supported.
# =>    ╭─[entry #32:1:10]
# =>  1 │ ["hello" "world"] | sort-by { length }
# =>    ·          ───┬───              ───┬──
# =>    ·             │                    ╰── only list<any>, binary, and nothing input data is supported
# =>    ·             ╰── input type: string
# =>    ╰────
```

We need a more robust way for commands to express how they handle the
`Type::Nothing` input case. I think a possible solution here is to allow
commands to express that they operate on `PipelineData::Empty`, rather
than `Value::Nothing`. Then, a command like `open` could have an empty
pipeline input type rather than a `Type::Nothing`, and the parse-time
and run-time pipeline input type checks know that `open` will safely
ignore an incorrectly typed input.

That being said, we have a release coming up and the above solution
might take a while to implement, so while unfortunate, bypassing input
type-checking for these problematic commands serves as a workaround to
avoid breaking changes in the release until a more robust solution is
implemented.

This PR bypasses input type-checking for the following commands:
* `load-env`: can take record of envvars as input or argument
* `nu-check`: checks input string or filename argument 
* `open`: can take filename as input or argument
* `polars when`: can be used with input, or can be chained with another
`polars when`
* `stor insert`: data record can be passed as input or argument
* `stor update`: data record can be passed as input or argument
* `format date`: `--list` ignores input value
* `into datetime`: `--list` ignores input value (also added a
`Type::Nothing` input which was missing from this command)

These commands have a similar input/output signature to the above
commands, but are working as intended:
* `cd`: The input/output signature was actually incorrect, `cd` always
ignores its input. I fixed this in this PR.
* `generate`
* `get`
* `history import` 
* `interleave`
* `into bool`
* `length`

# User-Facing Changes
<!-- List of all changes that impact the user experience here. This
helps us keep track of breaking changes. -->

As a temporary workaround, pipeline input type-checking for the
following commands has been bypassed to avoid undesirable run-time input
type checking errors which were previously not caught at parse-time:
* `open`
* `load-env`
* `format date`
* `into datetime`
* `nu-check`
* `stor insert`
* `stor update`
* `polars when`

# Tests + Formatting
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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` to
check that you're using the standard code style
- `cargo test --workspace` to check that all tests pass (on Windows make
sure to [enable developer
mode](https://learn.microsoft.com/en-us/windows/apps/get-started/developer-mode-features-and-debugging))
- `cargo run -- -c "use toolkit.nu; toolkit test stdlib"` to run the
tests for the standard library

> **Note**
> from `nushell` you can also use the `toolkit` as follows
> ```bash
> use toolkit.nu # or use an `env_change` hook to activate it
automatically
> toolkit check pr
> ```
-->
CI became green in the time it took me to type the description 😄 

# After Submitting
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N/A
2025-02-02 15:51:47 -05:00
2024-12-25 08:18:36 +08:00
2025-01-28 16:03:31 -06:00
2024-06-06 08:53:34 +08:00
2023-04-03 08:23:19 +12:00
2024-08-08 06:50:28 +08:00

Nushell

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

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

For details about which platforms the Nushell team actively supports, see our platform support policy.

Configuration

The default configurations can be found at sample_config which are the configuration files one gets when they startup Nushell for the first time.

It sets all of the default configuration to run Nushell. From here one can then customize this file for their specific needs.

To see where config.nu is located on your system simply type this command.

$nu.config-path

Please see our book for all of the Nushell documentation.

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.

The awesome-nu repo lists a variety of nu-plugins while the showcase repo shows off informative blog posts that have been written about Nushell along with videos that highlight technical topics that have been presented.

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.

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.

Description
A new type of shell
Readme MIT Cite this repository 110 MiB
Languages
Rust 96.9%
Nushell 2.9%