sig
type comparable
val ( >= ) : comparable -> comparable -> bool
val ( <= ) : comparable -> comparable -> bool
val ( = ) : comparable -> comparable -> bool
val ( > ) : comparable -> comparable -> bool
val ( < ) : comparable -> comparable -> bool
val ( <> ) : comparable -> comparable -> bool
val equal : comparable -> comparable -> bool
val compare : comparable -> comparable -> int
val ascending : comparable -> comparable -> int
val descending : comparable -> comparable -> int
val min : comparable -> comparable -> comparable
val max : comparable -> comparable -> comparable
end