tcfail179.hs:14:41: error:
    • Couldn't match type ‘x’ with ‘s’
      Expected: x -> s
        Actual: x -> x
      ‘x’ is a rigid type variable bound by
        a pattern with constructor:
          T :: forall s x. (s -> (x -> s) -> (x, s, Int)) -> T s,
        in a case alternative
        at tcfail179.hs:14:14-16
      ‘s’ is a rigid type variable bound by
        the type signature for:
          run :: forall s. T s -> Int
        at tcfail179.hs:12:1-17
    • In the second argument of ‘g’, namely ‘id’
      In the expression: g x id
      In a pattern binding: (x, _, b) = g x id
    • Relevant bindings include
        x :: s (bound at tcfail179.hs:14:26)
        g :: s -> (x -> s) -> (x, s, Int) (bound at tcfail179.hs:14:16)
        ts :: T s (bound at tcfail179.hs:13:5)
        run :: T s -> Int (bound at tcfail179.hs:13:1)