[swift-evolution] [proposal] Generic type aliases

Chris Lattner clattner at apple.com
Wed Mar 16 19:02:51 CDT 2016

On Mar 16, 2016, at 4:56 PM, Joe Groff <jgroff at apple.com> wrote:
>> We shouldn’t infer it the requirement.
>> Rationale: I see this as analogous (in two ways) to why we don’t infer hashability of T in:
>> func f<T>(…) {
>>   let x : Dictionary<T, String>
>> }
> However, we do infer the `T: Hashable` in a case like this:
> func foo<T>(x: Dictionary<T, String>) {}
> `typealias` feels similar to that to me. It doesn't have to be a global analysis, just an analysis of the RHS of the typealias.

I consider the RHS of the typealias to be the “body” of the type alias, and parameters to be part of the “signature” of the funcdecl.


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