## description
this pr adds [match
guards](https://doc.rust-lang.org/reference/expressions/match-expr.html#match-guards)
to match patterns
```nushell
match $x {
_ if $x starts-with 'nu' => {},
$x => {}
}
```
these work pretty much like rust's match guards, with few limitations:
1. multiple matches using the `|` are not (yet?) supported
```nushell
match $num {
0 | _ if (is-odd $num) => {},
_ => {}
}
```
2. blocks cannot be used as guards, (yet?)
```nushell
match $num {
$x if { $x ** $x == inf } => {},
_ => {}
}
```
## checklist
- [x] syntax
- [x] syntax highlighting[^1]
- [x] semantics
- [x] tests
- [x] clean up
[^1]: defered for another pr
# Description
Adds two more patterns when working with lists:
```
[1, ..$remainder]
```
and
```
[1, ..]
```
The first one collects the remaining items and assigns them into the
variable. The second one ignores any remaining values.
# User-Facing Changes
Adds more capability to list pattern matching.
# 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
- `cargo run -- crates/nu-utils/standard_library/tests.nu` 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
> ```
# 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.
# Description
Adds `|` patterns to `match`, allowing you to try multiple patterns for
the same case.
Example:
```
match {b: 1} { {a: $b} | {b: $b} => { print $b } }
```
Variables that don't bind are set to `$nothing` so that they can be
later checked.
This PR also:
fixes#8631
Creates a set of integration tests for pattern matching also
# User-Facing Changes
Adds `|` to `match`. Fixes variable binding scope.
# 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
> **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
> ```
# 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.
