prefer-map-over-and-then

Prefer Result map methods when chaining only rewraps one variant

A Result chain that always rebuilds the same variant cannot introduce the opposite outcome.
Instead, you SHOULD use map or mapErr and return the transformed payload directly.

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

Reported

function length(result: Result<string, int32>): Result<isize, int32> {
    return result.andThen((value) => Result.ok(value.length));
}
Accepted

function length(result: Result<string, int32>): Result<isize, int32> {
    return result.map((value) => value.length);
}
Prior art

- Clippy · bindinsteadofmap

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