fact: Fixpoint strcmp (s1 s2 : string) : SOrdering := match s1, s2 with | EmptyString, EmptyString => SEQ | EmptyString, String _ _ => SLT | String _ _, EmptyString => SGT | String ch1 s1', String ch2 s2' => match AsciiOT.compare ch1 ch2 with | LT _ => SLT | EQ _ => strcmp s1' s2' | GT _ => SGT end end.
imports: OrderedType Bool Ascii NArith Coq.Strings.String