T14580.hs:8:32: error:
    • Couldn't match kind ‘b’ with ‘a -> *’
      Expected kind ‘Cat a’, but ‘iso :: cat a b’ has kind ‘cat a b’
    • In the first argument of ‘ISO’, namely ‘(iso :: cat a b)’
      In the type ‘ISO (iso :: cat a b)’
      In the type declaration for ‘<-->’