[swift-evolution] [Pitch] Moving where Clauses Out Of Parameter Lists

[Timothy Wood]

> On Apr 6, 2016, at 11:48 AM, Sean Heber via swift-evolution <swift-evolution at swift.org> wrote:
> 
> This almost seems like it could work so that it didn't even need the bracketed parts to be able to figure out the types:
> 
> func anyCommonElements(lhs: T, _ rhs: U) -> Bool where
>    T : SequenceType,
>    U : SequenceType,
>    T.Generator.Element: Equatable,
>    T.Generator.Element == U.Generator.Element
> {}
> 

... though if there are no type constraints, this would be ambiguous:

	// If there are no know types T and R in scope, is this an error or are T and R assumed to be unconstrained generic parameters?
	func f(arg: T) -> R

-tim