Hello,
My two cents: I feel uncomfortable with SequenceType.first since SequenceType
clearly states that it may be destructed on iteration.
Compare :
seq.generate().next() // clear that it may give another result if called twice
seq.first // unclear that it may give another result if called twice
Gwendal
> Le 31 déc. 2015 à 00:57, Kevin Ballard via swift-evolution
> <swift-evolution@swift.org> a écrit :
>
> It's sometimes useful to get the first element of a sequence. To that end I'd
> like to propose
>
> extension SequenceType {
> /// Returns the first element of `self`, or `nil` if `self` is empty.
> /// - Complexity: O(1)
> var first: Self.Generator.Element? {
> var gen = generate()
> return gen.next()
> }
> }
>
> I think it makes sense to add this property to the definition of SequenceType
> as well, so various sequences can override it to avoid constructing a
> generator.
>
> With this added to SequenceType, we can remove it from CollectionType, as the
> behavior will be the same.
>
> -Kevin Ballard
>
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