[swift-evolution] Proposal: Add SequenceType.first

[Daniel Duan]

Users who don’t get the single-pass nature of SequenceType may expect a .last as well.

> On Dec 30, 2015, at 3:57 PM, Kevin Ballard via swift-evolution <swift-evolution at swift.org> wrote:
> 
> 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
> 
> _______________________________________________
> swift-evolution mailing list
> swift-evolution at swift.org
> https://lists.swift.org/mailman/listinfo/swift-evolution

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.swift.org/pipermail/swift-evolution/attachments/20151230/4a42de4a/attachment.html>