std/iter scan: change closure signature to be consistent with reduce (#14596)

# Description

I noticed that `std/iter scan`'s closure has the order of parameters
reversed compared to `reduce`, so changed it to be consistent.

Also it didn't have `$acc` as `$in` like `reduce`, so fixed that as
well.

# User-Facing Changes

> [!WARNING]
> This is a breaking change for all operations where order of `$it` and
`$acc` matter.

-   This is still fine.
    ```nushell
    [1 2 3] | iter scan 0 {|x, y| $x + $y}
    ```

-   This is broken
    ```nushell
    [a b c d] | iter scan "" {|x, y| [$x, $y] | str join} -n
    ```
    and should be changed to either one of these
    -   ```nushell
        [a b c d] | iter scan "" {|it, acc| [$acc, $it] | str join} -n
        ```
    -   ```nushell
        [a b c d] | iter scan "" {|it| append $it | str join} -n
        ```

# Tests + Formatting
Only change is in the std and its tests
- 🟢 toolkit test stdlib

# After Submitting
Mention in release notes
This commit is contained in:
Bahex 2024-12-16 15:13:51 +03:00 committed by GitHub
parent 3760910f0b
commit cfdb4bbf25
No known key found for this signature in database
GPG key ID: B5690EEEBB952194
2 changed files with 9 additions and 4 deletions

View file

@ -101,8 +101,9 @@ export def intersperse [ # -> list<any>
# Returns a list of intermediate steps performed by `reduce`
# (`fold`). It takes two arguments, an initial value to seed the
# initial state and a closure that takes two arguments, the first
# being the internal state and the second the list element in the
# current iteration.
# being the list element in the current iteration and the second
# the internal state.
# The internal state is also provided as pipeline input.
#
# # Example
# ```
@ -123,7 +124,8 @@ export def scan [ # -> list<any>
--noinit(-n) # remove the initial value from the result
] {
reduce --fold [$init] {|it, acc|
$acc ++ [(do $fn ($acc | last) $it)]
let acc_last = $acc | last
$acc ++ [($acc_last | do $fn $it $acc_last)]
}
| if $noinit {
$in | skip

View file

@ -49,7 +49,10 @@ def iter_scan [] {
let scanned = ([1 2 3] | iter scan 0 {|x, y| $x + $y})
assert equal $scanned [0, 1, 3, 6]
let scanned = ([a b c d] | iter scan "" {|x, y| [$x, $y] | str join} -n)
let scanned = ([a b c d] | iter scan "" {|it, acc| [$acc, $it] | str join} -n)
assert equal $scanned ["a" "ab" "abc" "abcd"]
let scanned = ([a b c d] | iter scan "" {|it, acc| append $it | str join} -n)
assert equal $scanned ["a" "ab" "abc" "abcd"]
}