Minor Iterator::filter_map description rewording.

[frewsxcv]

Fixes #39294.

[rust-highfive]

r? @BurntSushi

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[frewsxcv]

r? @QuietMisdreavus

[QuietMisdreavus]

@bors r+ rollup

[bors]

📌 Commit e29c020 has been approved by QuietMisdreavus

[frewsxcv]

@bors r-

i thought about this again. consider this code:

["1", "foo", "3"]
    .iter()
    .filter_map(|n| n.parse::<i32>())
    .collect()

here's how you'd implement it with filter then map:

["1", "foo", "3"]
    .iter()
    .filter(|n| n.parse::<i32>().is_some())
    .map(|n| n.parse::<i32>().unwrap())
    .collect()

i can't think of a way to implement it with map then filter:

["1", "foo", "3"]
    .iter()
    .map(|n| n.parse::<i32>())
    .filter(|n| n.is_some())
    .collect()  // [Some(1), Some(3)]

so i think you're idea to do "filter and map" might be a better suggestion here. what do you think?

[QuietMisdreavus]

The linked issue says it in terms of map(your_closure_here).filter(is_some).map(unwrap), so by that formulation it's technically map.filter.map. By saying "filter and map" you somewhat lose the ordering implied in the docs as-is, but even your own "map with filter" is better than what's there right now. I'm fine with either suggestion (though i am somewhat partial to the rhythm of "filter and map" >_>).

[frewsxcv]

agreed with everything you said;switched to "map with filter"

@bors r=QuietMisdreavus

[bors]

📌 Commit aac3008 has been approved by QuietMisdreavus

[bors]

⌛ Testing commit aac3008 with merge 77213e740777020ee48e0d5f40ac033df2e908bb...

[bors]

💔 Test failed - status-appveyor

[kennytm]

@bors retry #43985

[bors]

⌛ Testing commit aac3008 with merge 498a8f3...

[bors]

☀️ Test successful - status-appveyor, status-travis
Approved by: QuietMisdreavus
Pushing 498a8f3 to master...