Require Bool.
Local Open Scope char.
Local Open Scope N.
(** Total order on characters. *)
Definition compare (x y : Ascii.ascii) : comparison :=
N.compare (Ascii.N_of_ascii x) (Ascii.N_of_ascii y).

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