prefer-find-map

Prefer findMap over separate mapping and search operations

Mapping before a search creates a separate Iterator adapter and traversal state.
Instead, you SHOULD call findMap to transform values until the first defined result is produced.

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

Reported

function firstDefined(values: (int32 | undefined)[]): int32 | undefined {
    return values
        .iterator()
        .map((value) => value)
        .find((value) => value !== undefined);
}
Accepted

function firstDefined(values: (int32 | undefined)[]): int32 | undefined {
    return values
        .iterator()
        .findMap((value) => value);
}
Prior art

- Clippy · filtermapnext
- Clippy · manualfindmap

language/linter/src/rules/performance/preferfindmap.rs:8