T14507.hs:20:9: error:
    • Iceland Jack!  Iceland Jack! Stop torturing me!
      Pattern-bound variable x :: TypeRep a
        has a type that mentions pattern-bound coercion: co
      Hint: use -fprint-explicit-coercions to see the coercions
      Probable fix: add a pattern signature
    • In the declaration for pattern synonym ‘SO’