prefer-first-last

Prefer first and last accessors over equivalent indexing

array.at(0) and array.at(-1) duplicate the optional first and last endpoint lookups.
array.at(array.length - 1) also duplicates last.
Instead, you SHOULD use the corresponding endpoint accessor.

Trapping subscript access has different empty-array behavior and remains unchanged.

- Category: style
- Level: warning
- Fix: automatic
- Scope: module

Reported

function first(values: int32[]): int32 | undefined {
    return values.at(0);
}
Accepted

function first(values: int32[]): int32 | undefined {
    return values.first();
}
Prior art

- Clippy · getfirst
- Clippy · getlastwithlen

language/linter/src/rules/style/preferfirstlast.rs:8