# Description
Lint: `clippy::uninlined_format_args`
More readable in most situations.
(May be slightly confusing for modifier format strings
https://doc.rust-lang.org/std/fmt/index.html#formatting-parameters)
Alternative to #7865
# User-Facing Changes
None intended
# Tests + Formatting
(Ran `cargo +stable clippy --fix --workspace -- -A clippy::all -D
clippy::uninlined_format_args` to achieve this. Depends on Rust `1.67`)
# Description
Support extended unicode escapes in strings with same syntax as Rust:
`"\u{6e}"`.
# User-Facing Changes
New syntax in string literals, `\u{NNNNNN}`, to go along with the
existing `\uNNNN`.
New syntax accepts 1-6 hex digits and rejects values greater than
0x10FFFF (max Unicode char)..
_(List of all changes that impact the user experience here. This helps
us keep track of breaking changes.)_
Won't break existing scripts, since this is new syntax.
We might consider deprecating `char -u`, since users can now embed
unicode chars > 0xFFFF with the new escape.
# Tests + Formatting
Several unit tests and one integration test added.
- [x] `cargo fmt --all -- --check` to check standard code formatting
(`cargo fmt --all` applies these changes)
Done
- [x] `cargo clippy --workspace -- -D warnings -D clippy::unwrap_used -A
clippy::needless_collect` to check that you're using the standard code
style
Done
- [x] `cargo test --workspace` to check that all tests pass
Done
# 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
This adds the `SyntaxShape::Decimal` so you can create custom commands
with `decimal` types such as:
```shell
def cmd [x:decimal] { echo $x }
```
/cc @kurokirasama
Internally this is a little messy since we have `Type::Float` and
`SyntaxShape::Decimal`. I originally named it `float` and
`SyntaxShape::Float` but since we have `into decimal` and `1.1 |
describe` reports `decimal`, I decided to change the SyntaxShape.
# User-Facing Changes
_(List of all changes that impact the user experience here. This helps
us keep track of breaking changes.)_
# 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.
# Description
This PR makes changes that allow underscores in numbers.
Example:
```nu
# allows underscores to be placed arbitrarily to enhance readability.
let pi = 3.1415_9265_3589_793
# works with integers
let num = 1_000_000_000_000
let fav_color = 0x68_9d_6a
```
Add recursion limit to `def` and `block`.
Summary of this PR , it will detect if `def` call itself or not .
Then execute by using `stack` which I think best choice to use with this
design and core as it is available in all crates and mutable and
calculate the recursion limit on calling `def`.
Set 50 as recursion limit on `Config`.
Add some tests too .
Fixes#5899
Co-authored-by: Reilly Wood <reilly.wood@icloud.com>
# Description
This closes#7498, as well as fixes an issue reported in
https://github.com/nushell/nushell/pull/7002#issuecomment-1368340773
BEFORE:
```
〉[{foo: 'bar'} {}] | get foo
Error: nu:🐚:column_not_found (link)
× Cannot find column
╭─[entry #5:1:1]
1 │ [{foo: 'bar'} {}] | get foo
· ────────┬──────── ─┬─
· │ ╰── value originates here
· ╰── cannot find column 'Empty cell'
╰────
〉[{foo: 'bar'} {}].foo
╭───┬─────╮
│ 0 │ bar │
│ 1 │ │
╰───┴─────╯
```
AFTER:
```
〉[{foo: 'bar'} {}] | get foo
Error: nu:🐚:column_not_found (link)
× Cannot find column
╭─[entry #1:1:1]
1 │ [{foo: 'bar'} {}] | get foo
· ─┬ ─┬─
· │ ╰── cannot find column 'foo'
· ╰── value originates here
╰────
〉[{foo: 'bar'} {}].foo
Error: nu:🐚:column_not_found (link)
× Cannot find column
╭─[entry #3:1:1]
1 │ [{foo: 'bar'} {}].foo
· ─┬ ─┬─
· │ ╰── cannot find column 'foo'
· ╰── value originates here
╰────
```
EDIT: This also changes the semantics of `get`/`select` `-i` somewhat.
I've decided to leave it like this because it works more intuitively
with `default` and `compact`.
BEFORE:
```
〉[{a:1} {b:2} {a:3}] | select -i foo | to nuon
null
```
AFTER:
```
〉[{a:1} {b:2} {a:3}] | select -i foo | to nuon
[[foo]; [null], [null], [null]]
```
# User-Facing Changes
See above. EDIT: the issue with holes in cases like ` [{foo: 'bar'}
{}].foo.0` versus ` [{foo: 'bar'} {}].0.foo` has been resolved.
# 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.
# Description
Closes#7273.
Also slightly edits/tidies up parser.rs.
# User-Facing Changes
`^` is now forbidden in `def` and `def-env` command names. EDIT: also
`alias`.
# 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.
# Description
Prevent a situation where a `def` can't be run due to a poor choice of
name. Related: #6335. Hashtags, numbers and filesizes are no longer
allowed. `alias` check has been moved because previously `alias 123`
would be caught but `alias "123"` would be permitted.
# User-Facing Changes
Some definitions can no longer be made, but because they couldn't be run
previously anyway, it doesn't really matter.
# 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.
# Description
We've added some shapes recently. This PR adds them to the
default_config and sorts them in order to make finding missing ones
easier.
# User-Facing Changes
# 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.
# Description
This PR adds missing items in `parse_shape_name`, sorts the
`SyntaxShape` enum and the `Type` enum. It's a pain to hunt around for
particular items in an enum when they're unsorted.
# User-Facing Changes
# 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.
# Description
Fixes#6773.
```
/home/gabriel/CodingProjects/nushell〉ls -r 12/12/2022 02:57:35 PM
Error: nu::parser::unknown_flag (link)
× The `ls` command doesn't have flag `-r`.
╭─[entry #1:1:1]
1 │ ls -r
· ┬
· ╰── unknown flag
╰────
help: Available flags: --help(-h), --all(-a), --long(-l), --short-names(-s), --full-paths(-f), --du(-d), --directory(-D). Use `--help` for more information.
```
# User-Facing Changes
Different error for unknown flag.
# 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.
Reverts nushell/nushell#7448
Some surprising behavior in how we do this. For example:
```
〉if (true || false) { print "yes!" } else { print "no!" }
no!
〉if (true or false) { print "yes!" } else { print "no!" }
yes!
```
This means for folks who are using the old `||`, they possibly get the
wrong answer once they upgrade. I don't think we can ship with that as
it will catch too many people by surprise and just make it easier to
write buggy code.
# Description
We got some feedback from folks used to other shells that `try/catch`
isn't quite as convenient as things like `||`. This PR adds `&&` as a
synonym for `;` and `||` as equivalent to what `try/catch` would do.
# User-Facing Changes
Adds `&&` and `||` pipeline operators.
# 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.
# Description
This PR moves the `where` command to a parser keyword. While it still
uses the shape-directed parsing dictated by the signature, we're free to
change the parsing code now to a custom one once we remove the syntax
shapes.
As a side effect, the `where -b` flag was removed and its functionality
has moved to the new `filter` command.
Just FYI, other commands that take row conditions:
- `take until`
- `take while`
- `skip until`
- `skip while`
- `any`
- `all`
We can either move these to the parser as well or make them accept a
closure instead of row condition.
# User-Facing Changes
New `filter` command which replaces `where -b` functionality.
# 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.
# Description
Fixes#7407.
```
/home/gabriel/CodingProjects/nushell〉if false { 'a' } else { $foo } 12/09/2022 08:14:48 PM
Error: nu::parser::variable_not_found (link)
× Variable not found.
╭─[entry #1:1:1]
1 │ if false { 'a' } else { $foo }
· ──┬─
· ╰── variable not found
╰────
```
# User-Facing Changes
_(List of all changes that impact the user experience here. This helps
us keep track of breaking changes.)_
# 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.
# Description
Adds improved errors for when a user uses a bashism that nu doesn't
support.
fixes#7237
Examples:
```
Error: nu::parser::shell_andand (link)
× The '&&' operator is not supported in Nushell
╭─[entry #1:1:1]
1 │ ls && ls
· ─┬
· ╰── instead of '&&', use ';' or 'and'
╰────
help: use ';' instead of the shell '&&', or 'and' instead of the boolean '&&'
```
```
Error: nu::parser::shell_oror (link)
× The '||' operator is not supported in Nushell
╭─[entry #8:1:1]
1 │ ls || ls
· ─┬
· ╰── instead of '||', use 'try' or 'or'
╰────
help: use 'try' instead of the shell '||', or 'or' instead of the boolean '||'
```
```
Error: nu::parser::shell_err (link)
× The '2>' shell operation is 'err>' in Nushell.
╭─[entry #9:1:1]
1 │ foo 2> bar.txt
· ─┬
· ╰── use 'err>' instead of '2>' in Nushell
╰────
```
```
Error: nu::parser::shell_outerr (link)
× The '2>&1' shell operation is 'out+err>' in Nushell.
╭─[entry #10:1:1]
1 │ foo 2>&1 bar.txt
· ──┬─
· ╰── use 'out+err>' instead of '2>&1' in Nushell
╰────
help: Nushell redirection will write all of stdout before stderr.
```
# User-Facing Changes
**BREAKING CHANGES**
This removes the `&&` and `||` operators. We previously supported by
`&&`/`and` and `||`/`or`. With this change, only `and` and `or` are
valid boolean operators.
# 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.
# Description
fixes#7384
This is a stop-gap fix until we remove type-directed parsing. With this,
you can create a `OneOf` shape that can be one of a list of syntax
shapes. This gives you a little more control than you get with `Any`,
allowing you to add `Block` without breaking other parsing rules.
# User-Facing Changes
`else` block will no longer capture variables as it will now use a block
instead of a closure.
# 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.
# Description
Closes#7110. ~~Note that unlike "real" `mut` vars, $env can be deeply
mutated via stuff like `$env.PYTHON_IO_ENCODING = utf8` or
`$env.config.history.max_size = 2000`. So, it's a slightly awkward
special case, arguably justifiable because of what $env represents (the
environment variables of your system, which is essentially "outside"
normal Nushell regulations).~~
EDIT: Now allows all `mut` vars to be deeply mutated using `=`, on
request.
# User-Facing Changes
See above.
# 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.
Also enforce this by #[non_exhaustive] span such that going forward we
cannot, in debug builds (1), construct invalid spans.
The motivation for this stems from #6431 where I've seen crashes due to
invalid slice indexing.
My hope is this will mitigate such senarios
1. https://github.com/nushell/nushell/pull/6431#issuecomment-1278147241
# Description
(description of your pull request here)
# Tests
Make sure you've done the following:
- [ ] Add tests that cover your changes, either in the command examples,
the crate/tests folder, or in the /tests folder.
- [ ] Try to think about corner cases and various ways how your changes
could break. Cover them with tests.
- [ ] If adding tests is not possible, please document in the PR body a
minimal example with steps on how to reproduce so one can verify your
change works.
Make sure you've run and fixed any issues with these commands:
- [x] `cargo fmt --all -- --check` to check standard code formatting
(`cargo fmt --all` applies these changes)
- [ ] `cargo clippy --workspace --features=extra -- -D warnings -D
clippy::unwrap_used -A clippy::needless_collect` to check that you're
using the standard code style
- [ ] `cargo test --workspace --features=extra` to check that all the
tests pass
# Documentation
- [ ] If your PR touches a user-facing nushell feature then make sure
that there is an entry in the documentation
(https://github.com/nushell/nushell.github.io) for the feature, and
update it if necessary.
We already have the binary `bit-xor` and the shortcircuiting logical
`or`(`||`) and `and`(`&&`).
This introduces `xor` as a compact form for both brevity and clarity.
You can express the operation through `not`/`and`/`or` with a slight
risk of introducing bugs through typos.
Operator precedence
`and` > `xor` > `or`
Added logic and precedence tests.
# Description
This PR is a response to the issues raised in
https://github.com/nushell/nushell/pull/7087. It consists of two
changes:
* `export-env`, when evaluated in `overlay use`, will see the original
environment. Previously, it would see the environment from previous
overlay activation.
* Added a new `--reload` flag that reloads the overlay. Custom
definitions will be kept but the original definitions and environment
will be reloaded.
This enables a pattern when an overlay is supposed to shadow an existing
environment variable, such as `PROMPT_COMMAND`, but `overlay use` would
keep loading the value from the first activation. You can easily test it
by defining a module
```
module prompt {
export-env {
let-env PROMPT_COMMAND = (date now | into string)
}
}
```
Calling `overlay use prompt` for the first time changes the prompt to
the current time, however, subsequent calls of `overlay use` won't
change the time. That's because overlays, once activated, store their
state so they can be hidden and restored at later time. To force-reload
the environment, use the new flag: Calling `overlay use --reload prompt`
repeatedly now updates the prompt with the current time each time.
# User-Facing Changes
* When calling `overlay use`, if the module has an `export-env` block,
the block will see the environment as it is _before_ the overlay is
activated. Previously, it was _after_.
* A new `overlay use --reload` flag.
# 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.
# Description
Since we're not implementing `&&` or `||`, let's remove their pipeline
elements.
# User-Facing Changes
Nothing user facing. These were not yet implemented.
# 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.
# Description
This is a set of fixes to `err>` to make it work a bit more predictably.
I've also revised the tests, which accidentally tested the wrong thing
for redirection, but should be more correct now.
# User-Facing Changes
_(List of all changes that impact the user experience here. This helps
us keep track of breaking changes.)_
# 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.
# Description
rust 1.65.0 has been released for a while, this pr applies lint
suggestions from rust 1.65.0.
# User-Facing Changes
N/A
# 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 --features=extra -- -D warnings -D
clippy::unwrap_used -A clippy::needless_collect` to check that you're
using the standard code style
- `cargo test --workspace --features=extra` 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.
# Description
As title, when execute external sub command, auto-trimming end
new-lines, like how fish shell does.
And if the command is executed directly like: `cat tmp`, the result
won't change.
Fixes: #6816Fixes: #3980
Note that although nushell works correctly by directly replace output of
external command to variable(or other places like string interpolation),
it's not friendly to user, and users almost want to use `str trim` to
trim trailing newline, I think that's why fish shell do this
automatically.
If the pr is ok, as a result, no more `str trim -r` is required when
user is writing scripts which using external commands.
# User-Facing Changes
Before:
<img width="523" alt="img"
src="https://user-images.githubusercontent.com/22256154/202468810-86b04dbb-c147-459a-96a5-e0095eeaab3d.png">
After:
<img width="505" alt="img"
src="https://user-images.githubusercontent.com/22256154/202468599-7b537488-3d6b-458e-9d75-d85780826db0.png">
# 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 --features=extra -- -D warnings -D
clippy::unwrap_used -A clippy::needless_collect` to check that you're
using the standard code style
- `cargo test --workspace --features=extra` 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.
This adds new pipeline connectors called out> and err> which redirect either stdout or stderr to a file. You can also use out+err> (or err+out>) to redirect both streams into a file.
This adds support for (limited) mutable variables. Mutable variables are created with mut much the same way immutable variables are made with let.
Mutable variables allow mutation via the assignment operator (=).
❯ mut x = 100
❯ $x = 200
❯ print $x
200
Mutable variables are limited in that they're only tended to be used in the local code block. Trying to capture a local variable will result in an error:
❯ mut x = 123; {|| $x }
Error: nu::parser::expected_keyword (link)
× Capture of mutable variable.
The intent of this limitation is to reduce some of the issues with mutable variables in general: namely they make code that's harder to reason about. By reducing the scope that a mutable variable can be used it, we can help create local reasoning about them.
Mutation can occur with fields as well, as in this case:
❯ mut y = {abc: 123}
❯ $y.abc = 456
❯ $y
On a historical note: mutable variables are something that we resisted for quite a long time, leaning as much as we could on the functional style of pipelines and dataflow. That said, we've watched folks struggle to work with reduce as an approximation for patterns that would be trivial to express with local mutation. With that in mind, we're leaning towards the happy path.
