{-# LANGUAGE PatternSynonyms #-}
{-# LANGUAGE NamedFieldPuns #-}

pattern Arrow t1 t2 = App "->"    [t1, t2]
pattern Arrow{t1,t2} = App "->"    [t1,t2]
pattern Arrow{t1
             , t2} = App "->" [t1, t2]
pattern Int         =
  App "Int"   []
pattern Maybe{t}    =
  App
    "Maybe"
    [t]
pattern Maybe t     =
  App
    "Maybe"
    [t]

pattern a :< b <-
  (a , b)