lexically-scoped type variables in GHC 6.6

[Ross Paterson]

With reference to the documentation that just appeared in darcs:

Result type signatures are now equivalent to attaching the signature
to the rhs, i.e. redundant.

How about finishing the decoupling of type variable binding from pattern
type signatures by introducing an (optional) pattern form

	forall v1 ... vk. C p1 ... pn

mimicking the datatype declaration for an existential (with vi scoping
over pj, guards, where decls and the rhs), so the example would become

	data T = forall a. MkT [a]

	k :: T -> T
	k (forall a. MkT [t]) = MkT t3
		where
		t3::[a] = [t,t,t]