> On Nov 11, 2017, at 9:49 AM, Michel Fortin via swift-evolution
> <swift-evolution@swift.org> wrote:
>
> I think it fits well for arrays. Not sure about optionals.
This proposal only suggests changing the one on sequences, and even then, not
all of them. Currently, the following exist:
// Reminder: Int("someString") returns 'Int?' in the following examples
// (1) Sequence.flatMap() with a closure returning an optional, dropping
anything that maps to nil
["1", "mountain", "2"].flatMap({ Int($0) }) // [1, 2]
// (2) Sequence.flatMap() with a closure returning a sequence, then joining
(“flattening”) them into one array
[1, 2, 3].flatMap({ Array(1...$0) }) // [1, 1, 2, 1, 2, 3]
// (3) Optional.flatMap() with a closure returning an optional, flattening a
nested optional.
("3" as String?).flatMap({ Int($0) }) // Optional(3)
The 2nd and 3rd variants are both about flattening nested structures, and would
not change under this proposal. We would keep calling them “flatMap()”. There
is no a proposal to add Optional.filterMap, nor to change the Sequence.flatMap
variant that flattens nested sequences. The only change proposed it is to
rename the first one.
-BJ_______________________________________________
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