src/HOL/Tools/Nitpick/minipick.ML

        | Const (@{const_name fst}, _) => raise SAME ()
        | Const (@{const_name snd}, _) $ _ => raise SAME ()
        | Const (@{const_name snd}, _) => raise SAME ()
        | Const (_, @{typ bool}) => atom_from_formula (to_F Ts t)
        | Free (x as (_, T)) =>
-         Rel (arity_of RRep card T, find_index (equal x) frees)
+         Rel (arity_of RRep card T, find_index (curry (op =) x) frees)
        | Term.Var _ => raise NOT_SUPPORTED "schematic variables"
        | Bound j => raise SAME ()
        | Abs (_, T, t') =>
          (case fastype_of1 (T :: Ts, t') of
             @{typ bool} => Comprehension (decls_for SRep card Ts T,