
tcfail076.hs:18:82:
    Couldn't match type `res' with `res1'
      `res' is a rigid type variable bound by
            a type expected by the context: (a -> m res) -> m res
            at tcfail076.hs:18:28
      `res1' is a rigid type variable bound by
             a type expected by the context: (b -> m res1) -> m res1
             at tcfail076.hs:18:64
    Expected type: m res1
      Actual type: m res
    In the return type of a call of `cont'
    In the expression: cont a
