T9017.hs:8:7: error:
    • Couldn't match kind ‘k’ with ‘*’
      ‘k’ is a rigid type variable bound by
        the type signature for:
          foo :: forall k k1 (a :: k -> k1 -> *) (b :: k) (m :: k -> k1).
                 a b (m b)
        at T9017.hs:7:1-16
      When matching the kind of ‘a’
    • In the expression: arr return
      In an equation for ‘foo’: foo = arr return
    • Relevant bindings include
        foo :: a b (m b) (bound at T9017.hs:8:1)