Kind Annotations

Ghc permits type expressions (or is it only type variables?) to be annotated with a kind signature. See  this section of the ghc user guide.

type T (f :: * -> *) = f Int

Pros

• Without the ability to write a kind signature, there are cases where one must introduce dummy data constructors purely for their effect in forcing a higher-kindedness on a type variable.

Cons

• con

Proposal

To adopt explicit kind annotations as part of the language, more or less exactly as ghc permits. Ticket: #84