fact: Definition is_digit (a:ascii) : bool := match Z.compare (Z_of_ascii a) (Z_of_ascii "0"%char) with Lt => false | Eq => true | Gt => match Z.compare (Z_of_ascii a) (Z_of_ascii "9"%char) with Gt => false | _ => true end end.
imports: String Ascii List ZArith little_w_string