T18398.hs:13:34: error:
    • No instance for (C Ex p0) arising from a use of ‘meth’
    • In the expression: meth x y
      In a case alternative: MkEx _ -> meth x y
      In the expression: case x of MkEx _ -> meth x y

T18398.hs:13:70: error:
    • No instance for (C Ex p0) arising from a use of ‘meth’
    • In the expression: meth x z
      In a case alternative: MkEx _ -> meth x z
      In the expression: case x of MkEx _ -> meth x z