Tracking Issue for Iterator::find_map

[KodrAus]

Iterator::find_map, like filter_map but for the first matching item in the iterator.

Implemented in #49098

cc @matklad

[Amanieu]

I found this method useful when I had an array of several BinaryHeaps from which I needed to pop one item:

while let Some(work_item) = work_lists.iter_mut().find_map(|h| h.pop()) {
    ...
}

Additionally, the order of the heaps in the array is significant, which this method handles perfectly (the first heap in the array has highest priority).

[shepmaster]

I have also found it useful.

Before

LENGTHS.flat_map(|length| {
    seeds
        .par_iter()
        .find_any(|&&seed| test_password(length, seed))
        .map(|&seed| (length, seed))
}).next()

After

LENGTHS.find_map(|length| {
    seeds
        .par_iter()
        .find_any(|&&seed| test_password(length, seed))
        .map(|&seed| (length, seed))
})

[matklad]

I wonder what are the next steps here? Are we ready to propose this for stabilization? If we are, what's the process? :)

[shepmaster]

what's the process? :)

Code mechanics wise: So you want to stabilize a feature?.

[KodrAus]

This is a handy little method for iterators, that @matklad nicely motivated in the original PR. Shall we stabilize?

@rfcbot fcp merge

Pessimistically cc'ing @rust-lang/libs in case rfcbot ignores me.

[alexcrichton]

@rfcbot fcp merge

Let's try again!

[rfcbot]

Team member @alexcrichton has proposed to merge this. The next step is review by the rest of the tagged teams:

• @Kimundi
• @SimonSapin
• @alexcrichton
• @dtolnay
• @sfackler
• @withoutboats

No concerns currently listed.

Once a majority of reviewers approve (and none object), this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up!

See this document for info about what commands tagged team members can give me.

[rfcbot]

🔔 This is now entering its final comment period, as per the review above. 🔔