# Description
Close: #12083Close: #12084
# User-Facing Changes
It's a breaking change because we have switched the position of
`<initial>` and `<closure>`, after the change, initial value will be
optional. So it's possible to do something like this:
```nushell
> let f = {|fib = [0, 1]| {out: $fib.0, next: [$fib.1, ($fib.0 + $fib.1)]} }
> generate $f | first 5
╭───┬───╮
│ 0 │ 0 │
│ 1 │ 1 │
│ 2 │ 1 │
│ 3 │ 2 │
│ 4 │ 3 │
╰───┴───╯
```
It will also raise error if user don't give initial value, and the
closure don't have default parameter.
```nushell
❯ let f = {|fib| {out: $fib.0, next: [$fib.1, ($fib.0 + $fib.1)]} }
❯ generate $f
Error: × The initial value is missing
╭─[entry #5:1:1]
1 │ generate $f
· ────┬───
· ╰── Missing intial value
╰────
help: Provide <initial> value in generate, or assigning default value to closure parameter
```
# Tests + Formatting
Added some test cases.
---------
Co-authored-by: Stefan Holderbach <sholderbach@users.noreply.github.com>
# Description
This PR renames the `unfold` command to `generate`.
closes#10760
# User-Facing Changes
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# Tests + Formatting
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