:set -XPolyKinds -XRankNTypes -XGADTs
data D1 = MkD1 (forall p (a :: k). p a -> Int)
data D2 = MkD2 (forall p a. p a -> Int)
data D3 = MkD3 (forall k p (a :: k). p a -> Int)
:i D2
:i D3