Support types with same name and different arities

[yurrriq]

As a user, I'd like to define a type foo/1 as well as a type foo/2:

type foo 'a = Nothing | Just 'a

type foo 'a 'b = Left 'a | Right 'b

[lpil]

What's the rationale for this? :)

[yurrriq]

A better example is perhaps list.

type list = list any

type list 'a = Nil | Cons 'a (list 'a)