equivariant functions

[Christopher Wright]

KennyTM~ wrote:
> Sorry, I can't think of an existing keyword that can clearly qualify the 
> purpose in this syntax (“stuff(Type) f(stuff(Type) s)”) either.
> 
> By the explanation argument, I actually mean what a programmer first 
> sees this feature think of. Presented with Andrei's “typeof” syntax, I 
> can at least guess what the function looks like (it returns the same 
> type as “s”, OK); but with “inout” I just stopped with "What the heck is 
> going on?!".

I can't:

typeof(s) foo(const(char)[] s)

This looks like it's shorthand for:
const(char)[] foo(const(char)[] s)

And the examples with typeof(A), where A is a type, just didn't make any 
sense.