Simpler syntax for exact-type extensions of generic types

[anthonylatsis]

The previous pitch: Allow static extensions of generic types to be written without where clauses

The main concern was about people potentially misinterpreting the shortcut as : Type rather than == Type.

@xwu

While I can fully appreciate why the proposed syntax must mean == and not : , the fact is that based on the reactions here from people very experienced in Swift, there is a question as to its meaning. This suggests that, should this idea be implemented, other users will have the same confusion.

It's not a matter of "if you don't like it you don't have to use it" because code is read more often than it is written. If even experienced users can misinterpret this shorthand, then we must give consideration as to whether its inclusion in the language will do more harm than good, especially here where misinterpreting == to mean : can lead to subtle errors.

[...]

However, consider the "obvious" (and wrong) way of writing an extension for an array of things that conform to P :

protocol P { }
extension Array<P> { /* ... */ }