Std proposal: Option::fold()

[scottmcm]

Previous discussion:

Lifting binary operations, e.g. T+T → Option<T> + Option<T>

Is there a simple way today to get the other kind lift, which turns a binary operation on T into a binary operation on Option<T>, respecting the new identity element None? fn lift<T, F: FnOnce(T, T) -> T>( f: F, left: Option<T>, right: Option<T>) -> Option<T> { match (left, right) { (None, right) => right, (left, None) => left, (Some(left), Some(right)) => Some(f(left, right)), } } This does the right thing for std::cmp::min, std::cmp::max. I think this is …