[swift-dev] [Questions][SE-143]Conditional conformances for protocols?

[Cao, Jiannan]

Recently, we can use conditional conformances for struct/class.

> extension Array: Equatable where Self.Element : Equatable { ... }


Could we use conditional conformances for protocols?
For example:

> extension Collection : Equatable  where Self.Element : Equatable { ... }


Thanks!
Jiannan