> On 22 Jul 2016, at 20:43, Jacob Bandes-Storch <jtban...@gmail.com> wrote:
>
>> On Fri, Jul 22, 2016 at 8:35 AM, Ben Rimmington <m...@benrimmington.com>
>> wrote:
>>
>>> On 22 Jul 2016, at 02:46, Jacob Bandes-Storch wrote:
>>>
>>> In the swift-lang Slack channel, a few of us were discussing
>>> joined(separator:) and realized that flatten() does almost exactly the same
>>> thing.
>>>
>>> Is there interest in renaming flatten() to joined()? Since joined takes a
>>> separator that's any Sequence, we can't have a default value for the
>>> separator parameter, but we can have a variant of joined() with no
>>> arguments.
>>
>> I'd like default separators for the joined() methods.
>>
>> <https://bugs.swift.org/browse/SR-1428>
>>
>> But renaming flatten() to joined() seems complicated.
>>
>> <https://github.com/apple/swift/blob/master/stdlib/public/core/Flatten.swift.gyb>
>> <https://github.com/apple/swift/blob/master/stdlib/public/core/Join.swift>
>
> What makes it seem complicated? At the very least, one could just rename the
> flatten() function. There might also be an opportunity to combine the two
> files and delete some code from stdlib.
There's only one joined() method (for a sequence of sequences):
extension Sequence {
func joined<Separator: Sequence>(separator: Separator) ->
JoinedSequence<Self>
}
There are many flatten() methods (`where` clauses omitted for brevity):
extension Sequence {
func flatten() -> FlattenSequence<Self>
}
extension LazySequenceProtocol {
func flatten() -> LazySequence<FlattenSequence<Self.Elements>>
}
extension LazyCollectionProtocol {
func flatten() -> LazyCollection<FlattenCollection<Self.Elements>>
}
extension Collection {
func flatten() -> FlattenCollection<Self>
}
extension BidirectionalCollection {
func flatten() -> FlattenBidirectionalCollection<Self>
}
So it's not a simple one-to-one rename.
When there's no `separator` argument, will FlattenIterator perform better than
JoinedIterator?
>> And what would happen to the flatMap() methods? Is flatten() a term of art?
>>
>> <https://github.com/apple/swift/blob/master/stdlib/public/core/FlatMap.swift>
>
> I'd say flatMap is more a "term of art" than flatten. "flatten" just
> describes literally what is being done. Frankly I'm surprised it was never
> named flattened(). Anyway, flatMap should stay.
## Future directions
Will the flatMap(_:) methods also have flatMap(separator:_:) variants?
-- Ben
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