lambdacube-2008.12.24: maybe.cube

Maybe :: * -> *;
Maybe a = forall (maybeT::*) . maybeT->(a->maybeT)->maybeT;

Nothing :: forall (a::*) . Maybe a;
Nothing a = \ (maybeT::*) (nothing::maybeT) (just::a->maybeT) -> nothing;

Just :: forall (a::*) . a -> Maybe a;
Just a x = \ (maybeT::*) (nothing::maybeT) (just::a->maybeT) -> just x;

maybe :: forall (a::*) (r::*) . r -> (a->r) -> Maybe a -> r;
maybe a r nothing just s = s r nothing just;