feat(array): narrow return type for first and last
#140
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crishoj
changed the title
first and lastfirst and last
aleclarson
reviewed
Jul 28, 2024
| @@ -11,9 +11,11 @@ | |||
| * // 0 | |||
| * ``` | |||
| */ | |||
| export function first<T>(array: readonly T[]): T | undefined | |||
| export function first(array: readonly []): undefined | |||
| export function first<T>(array: readonly T[]): T | |||
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Can't assume the length of the array type is not zero here, so return type has to be T | undefined. Or is your goal to align this with arr[0]-style access?
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It's the same case as #139 (comment)
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Agreed, invalid for similar reasons. Suggest closing.
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Summary
Similarly to #139, we can narrow the return types for
first()andlast()based on the emptiness of the argument.Before:
After:
For any code change,
Does this PR introduce a breaking change?
No