[swift-evolution] [SE-0011] Re-considering the replacement keyword for "typealias"

[Tino Heth]

> In fact why not just use the generics syntax with protocols ?  Anybody implementing a "Generic" Protocol has to specify the types.
That's a simple solution, but inconvenient:
One use case for placeholders (I don't use the official name here to propagate an alternative ;-) is when you have a types that depend on a parameter.
I'm to lazy to look up a real example, but Array<Int> is naturally associated with an enumerator for Int — and it is no fun to be forced to include such relationships all over the place.