T7368.hs:3:10: error: [GHC-18872]
    • Couldn't match kind ‘*’ with ‘* -> *’
      When matching types
        b0 :: *
        Maybe :: * -> *
      Expected: a0 -> b0
        Actual: c0 Maybe
    • In the first argument of ‘b’, namely ‘(l Nothing)’
      In the expression: b (l Nothing)
      In an equation for ‘f’: f = b (l Nothing)