On Tue, Nov 28, 2017 at 12:59 PM, Joe Groff via swift-evolution < swift-evolution@swift.org> wrote:
> > > > On Nov 28, 2017, at 10:52 AM, Vladimir.S <sva...@gmail.com> wrote: > > > > On 27.11.2017 20:28, Joe Groff via swift-evolution wrote: > >>> On Nov 20, 2017, at 5:43 PM, Chris Lattner via swift-evolution < > swift-evolution@swift.org <mailto:swift-evolution@swift.org>> wrote: > >>> > >>> > >>>> On Nov 20, 2017, at 5:39 PM, Kelvin Ma via swift-evolution < > swift-evolution@swift.org <mailto:swift-evolution@swift.org>> wrote: > >>>> > >>>> when SE-185 <https://github.com/apple/swift-evolution/blob/master/ > proposals/0185-synthesize-equatable-hashable.md> went through swift > evolution, it was agreed that the next logical step < > https://www.mail-archive.com/swift-evolution@swift.org/msg26162.html> is > synthesizing these conformances for tuple types, though it was left out of > the original proposal to avoid mission creep. I think now is the time to > start thinking about this. i’m also tacking on Comparable to the other two > protocols because there is precedent in the language from SE-15 < > https://github.com/apple/swift-evolution/blob/master/proposals/0015-tuple- > comparison-operators.md> that tuple comparison is something that makes > sense to write. > >>>> > >>>> EHC conformance is even more important for tuples than it is for > structs because tuples effectively have no workaround whereas in structs, > you could just manually implement the conformance. > >>> > >>> In my opinion, you’re approaching this from the wrong direction. The > fundamental problem here is that tuples can’t conform to a protocol. If > they could, synthesizing these conformances would be straight-forward. > >> It would be a tractable intermediate problem to introduce built-in > conformances for tuples (and perhaps metatypes) to > Equatable/Hashable/Comparable without breaching the more general topic of > allowing these types to have general protocol conformances. I think that > would cover the highest-value use cases. > > > > So, shouldn't we do this first step ASAP and then design a good common > solution to allow tuples/metatypes/funcs to confirm to custom protocols in > some next version of Swift? > > I really believe this is the good practical decision and will be > supported by community if such proposal will be on the table. > > Is there any drawback in such step? > > The expected behavior of tuple Equatable/Hashable/Comparable seems obvious > to me (though I could well be missing something), and any behavior we > hardcode should be naturally replaceable by a generalized conformance > mechanism, so it's primarily a "small matter of implementation". There > would be some implementation cost to managing the special case in the > compiler and runtime; the tradeoff seems worth it to me in this case, but > others might reasonably disagree. Not speaking for the entire core team, I > would personally support considering a proposal and implementation for > builtin tuple Equatable/Hashable/Comparable conformance. > > -Joe > _______________________________________________ > swift-evolution mailing list > swift-evolution@swift.org > https://lists.swift.org/mailman/listinfo/swift-evolution > i wouldn’t know how to implement this but i could write up this proposal in a few days
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