module PolySet:Reins.Sets.PolySetSigwith type ('a,'b) result = 'a * 'b PolySet.t
compare function internally and may not be
as efficient as the Reins.SplaySet.MonoSet module which allows the
use of a more efficient comparison function.type 'a t
type 'a cursor
type ('a, 'b) result
include Reins.Sets.Set_
val to_string : ('a -> string) -> 'a set -> string