ExplicitForAllRules1.hs:49:11: warning:
    Forall'd type variable ‘k’ is not bound in RULE lhs
      Orig bndrs: [k, a, b, x]
      Orig lhs: id' @a x
      optimised lhs: id' @a x
    Forall'd type variable ‘b’ is not bound in RULE lhs
      Orig bndrs: [k, a, b, x]
      Orig lhs: id' @a x
      optimised lhs: id' @a x

ExplicitForAllRules1.hs:49:31: warning: [-Wunused-foralls (in -Wextra)]
    Unused quantified type variable ‘b’
    in the rule "example7"