(* Note: The result of applying this functor does not satisfy the SET signature,
   because it is instantiated to a particular element type rather than working
   for any element type *)

module StandardSet (Ord: Set.OrderedType) = struct

  module SM = Set.Make(Ord)

  type set = SM.t
 
  let empty = SM.empty
  
  let singleton x = SM.singleton x

  let insert x s = SM.add x s

  let delete x s = SM.remove x s

  let member x s = SM.mem x s

  let union s1 s2 = SM.union s1 s2

  let intersection s1 s2 = SM.inter s1 s2

  let difference s1 s2 = SM.diff s1 s2

  let toList s = SM.elements s

  let fromList xs = List.fold_right SM.add xs SM.empty 

  let fromSexp eltFromSexp sexp = 
    match sexp with 
      Sexp.Seq elts -> fromList (List.map eltFromSexp elts)
    | _ -> raise (Failure "unrecognized s-expression")

  let toSexp eltToSexp s = Sexp.Seq(List.map eltToSexp (toList s))

  let toString eltToString s = 
    StringUtils.listToString eltToString (SM.elements s)

end