> Am 09.06.2016 um 18:49 schrieb Dave Abrahams via swift-evolution > <[email protected]>: > > > on Wed Jun 08 2016, Jordan Rose <[email protected]> wrote: > >>> On Jun 8, 2016, at 13:16, Dave Abrahams via swift-evolution >>> <[email protected]> wrote: >>> >>> >>> on Wed Jun 08 2016, Thorsten Seitz >> >>> <[email protected] >>> <mailto:[email protected]>> >>> wrote: >>> >>>> Ah, thanks, I forgot! I still consider this a bug, though (will have >>>> to read up again what the reasons are for that behavior). >>> >>> Yes, but in the case of the issue we're discussing, the choices are: >>> >>> 1. Omit from the existential's API any protocol requirements that depend >>> on Self or associated types, in which case it *can't* conform to >>> itself because it doesn't fulfill the requirements. >>> >>> 2. Erase type relationships and trap at runtime when they don't line up. >>> >>> Matthew has been arguing against #2, but you can't “fix the bug” without >>> it. >> >> #1 has been my preference for a while as well, at least as a starting >> point. > > I should point out that with the resyntaxing of existentials to > Any<Protocols...>, the idea that Collection's existential doesn't > conform to Collection becomes far less absurd than it was, so maybe this > is not so bad.
I think the problem is more that Any<Collection> does not conform to a specific value for a type parameter T: Collection What I mean by this is that `Collection` denotes a type family, a generic parameter `T: Collection` denotes a specific (though unknown) member of that type family and `Any<Collection>` denotes the type family again, so there is really no point in writing Any<Collection> IMO. The type family cannot conform to T because T is just one fixed member of it. It conforms to itself, though, as I can write let c1: Any<Collection> = … let c2: Any<Collection> = c1 That’s why I think that we could just drop Any<Collection> and simply write Collection. -Thorsten _______________________________________________ swift-evolution mailing list [email protected] https://lists.swift.org/mailman/listinfo/swift-evolution
