data Test a = forall b. Test (a -> b)

data Test2 a where
	Test2 :: Test a -> Test2 a

data Test3 a where
	Test3 :: (forall b. (a -> b)) -> Test3 a

test2 :: Test2 a
test2 = Test2 (Test id)

test3 :: Test3 a
test3 = Test3 id