T19709a.hs:8:8: error: [GHC-55287]
    • The first pattern in the equation for ‘levid’
      does not have a fixed runtime representation.
      Its type is:
        a :: TYPE r
    • In the expression:
        let
          levid :: forall (r :: RuntimeRep) (a :: TYPE r). a -> a
          levid x = x
        in return []