Tracking Issue for `Option::reduce`

Feature gate: #![feature(option_reduce)]

This is a tracking issue for Option::reduce, which combines two Options into one if both are Some, otherwise choosing the one that's Some or returning None.

ACP: rust-lang/libs-team#609

Public API

impl<T> Option<T> {
    fn reduce<U, R, F>(self, other: Option<U>, f: F) -> Option<R>
    where
        T: Into<R>,
        U: Into<R>,
        F: FnOnce(T, U) -> R,
    {
        match (self, other) {
            (Some(a), Some(b)) => Some(f(a, b)),
            (Some(a), _) => Some(a.into()),
            (_, Some(b)) => Some(b.into()),
            _ => None,
        }
    }
}

Steps / History

(Remember to update the S-tracking-* label when checking boxes.)

• Implementation: #144274
• Final comment period (FCP)^1
• Stabilization PR

Unresolved Questions

• Will this cause inference problems? https://github.com/rust-lang/libs-team/issues/609#issuecomment-3026494590

Start by reading implementation issue #144274 and the ACP discussion in rust-lang/libs-team#609, then review the unresolved inference question. The feature is done only when the final comment period and stabilization PR have been completed and the option_reduce gate can be stabilized.