(** Total order on characters. *)
Definition compare (x y : Ascii.ascii) : comparison :=
  N.compare (Ascii.N_of_ascii x) (Ascii.N_of_ascii y).

(* Specifications: *)
Lemma compare_implies_eq : forall (x y : Ascii.ascii), compare x y = Eq -> x = y.
Lemma compare_same_is_eq : forall (x : Ascii.ascii), compare x x = Eq.