Agreed, any proposal would come with an accompanying PR. Since the API itself is pretty straightforward, I don't think this will put any undue burden on the reviewers.
Austin > On Jan 3, 2016, at 12:09 AM, Dave Abrahams <dabrah...@apple.com> wrote: > > >> On Jan 2, 2016, at 9:44 PM, Austin Zheng via swift-evolution >> <swift-evolution@swift.org> wrote: >> >> Hello all, >> >> Currently there exist at least four 'type-erased' sequence/collection types: >> AnySequence, AnyForwardCollection, AnyBidirectionalCollection, and >> AnyRandomAccessCollection. >> >> The three Any*Collection types can be conceptually arranged into a 'ladder', >> in which collections can be constructed unconditionally from collection >> types above themselves, and conditionally from collection types below >> themselves. I've put together a little ASCII image of this here: >> (https://gist.github.com/austinzheng/829425242bef1573b668). >> >> Note that AnySequence doesn't currently fit into this ladder: Any*Collection >> instances can't easily be constructed from AnySequences. SR-119 >> (https://bugs.swift.org/browse/SR-119) aims to change that. As per that >> ticket, I propose that we add three promotion APIs, sketched out as >> following: >> >> extension AnyForwardCollection { >> init?<Element>(_: AnySequence< Element>) >> } >> >> extension AnyBidirectionalCollection { >> init?<Element>(_: AnySequence< Element>) >> } >> >> extension AnyRandomAccessCollection { >> init?<Element>(_: AnySequence< Element>) >> } >> >> Like their Any*Collection --> Any*Collection antecedents, these initializers >> construct a new Any*Collection out of an existing AnySequence, but only if >> the underlying sequence is compatible, and without copying the underlying >> sequence. >> >> I'll also have to examine SE-0014 >> (https://github.com/apple/swift-evolution/blob/master/proposals/0014-constrained-AnySequence.md) >> more closely to see if it has any effects on this proposal. >> >> I plan on submitting a formal proposal at some point (probably by the end of >> the coming week), but first wish to solicit feedback, opinions, concerns, >> etc. Thanks for your time. > > My main concern is whether you can implement it, and do so efficiently. I > don’t have a particular reason to think you can’t, but it seems simple enough > to check, so IMO such a proposal should come with an implementation. > > -Dave >
_______________________________________________ swift-evolution mailing list swift-evolution@swift.org https://lists.swift.org/mailman/listinfo/swift-evolution
