[swift-users] [swift-evolution] Request for information about constrained protocol inheritance

[Jens Persson]

Ah, thanks! Do you happen to know of any particular std lib protocol of the
form:
protocol P : OtherP where OtherP.AT ...
?

On Wed, Jul 5, 2017 at 7:53 AM, Xiaodi Wu <xiaodi.wu at gmail.com> wrote:

> Replying to swift-users as well, as it's probably the more appropriate
> forum.
>
> SE-0142 (Permit where clauses to constrain associated types) is what
> brought about this feature. It is now used in the standard library.
>
>
> On Wed, Jul 5, 2017 at 00:26 Jens Persson via swift-evolution <
> swift-evolution at swift.org> wrote:
>
>> The following compiles in Swift 4 (but not in Swift 3.1):
>>
>> protocol P1 {
>>     associatedtype A
>> }
>> protocol P2 : P1 where A == Int {
>> }
>>
>> I've not been able to find any proposal, discussion or documentation
>> mentioning it so any pointers to such would be greatly appreciated.
>>
>> Also, is this new feature used somewhere in the std lib?
>>
>> /Jens
>> _______________________________________________
>> swift-evolution mailing list
>> swift-evolution at swift.org
>> https://lists.swift.org/mailman/listinfo/swift-evolution
>>
>
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