data Maybe a = Nothing | Just a
data Either e a = Left e | Right a
data [a] = [] | a : [a]
newtype Identity a = Identity a
data Proxy a = Proxy
newtype Reader r a = Reader (r -> a))
newtype State s a = State (s -> (a, s))
newtype Parser a = Parser (String -> [(a,String)])
data IO a =  ¯\_(ツ)_/¯