Batteries user guide : BatSet.S.Labels

`sig val iter : f:(BatSet.S.elt -> unit) -> BatSet.S.t -> unit val fold : f:(BatSet.S.elt -> 'a -> 'a) -> BatSet.S.t -> init:'a -> 'a val for_all : f:(BatSet.S.elt -> bool) -> BatSet.S.t -> bool val exists : f:(BatSet.S.elt -> bool) -> BatSet.S.t -> bool val map : f:(BatSet.S.elt -> BatSet.S.elt) -> BatSet.S.t -> BatSet.S.t val filter : f:(BatSet.S.elt -> bool) -> BatSet.S.t -> BatSet.S.t val filter_map : f:(BatSet.S.elt -> BatSet.S.elt option) -> BatSet.S.t -> BatSet.S.t val partition : f:(BatSet.S.elt -> bool) -> BatSet.S.t -> BatSet.S.t * BatSet.S.t end`