Once-and-for-all implementations come in many flavors. For now, we have clear
interest in making a limited subset of possible tuples properly Comparable.
This will also make it easier to implement extensions to specific arities now
and serve as a base for variadic generics if that is the path we take. I could
certainly see Future Swift™ allowing this to sit side-by-side with the finite
version in this proposal, couldn't you?
extension (T...) : Equatable where T.Element : Equatable { }
func == <T : Equatable>(l : (T...), r : (T...)) -> Bool { /* .. */ }
~Robert Widmann
2016/05/04 0:54、Joe Groff <[email protected]> のメッセージ:
>
>> On May 3, 2016, at 9:52 PM, Robert Widmann <[email protected]> wrote:
>>
>> Trouble is that I don't want variadic generics without corresponding support
>> from the type system which is untenable without HKTs (see last paragraph of
>> proposal). C++'s variadic implementation of std::tuple is not elegant to my
>> mind, and would have no place in a library I could think of writing.
>
> I think we'd keep tuples as a builtin type. Variadics would just let you
> implement Equatable/Hashable/etc. once for all tuple arities. I don't see why
> we'd need HKTs for that.
>
> -Joe
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