T7368.hs:3:10: error:
    Couldn't match kind ‘* -> *’ with ‘*’
    When matching types
      c0 :: (* -> *) -> *
      (->) a0 :: * -> *
    Expected type: a0 -> b0
      Actual type: c0 Maybe
    In the first argument of ‘b’, namely ‘(l Nothing)’
    In the expression: b (l Nothing)