{-# LANGUAGE RankNTypes, ImpredicativeTypes, ScopedTypeVariables #-}

main = return ()


data Lam f = Lam f

helper =
  let a = Lam undefined :: Lam (forall a. a -> a)
      --b = Lam id        :: Lam (forall a. a -> a)
      --c = Lam id2       :: Lam (forall a. a -> a)
   in ()


id2 :: forall a. a -> a
id2 x = x