Batteries user guide : BatRef

`sig type 'a t = 'a Pervasives.ref external ref : 'a -> 'a Pervasives.ref = "%makemutable" external ( ! ) : 'a Pervasives.ref -> 'a = "%field0" external ( := ) : 'a Pervasives.ref -> 'a -> unit = "%setfield0" external set : 'a Pervasives.ref -> 'a -> unit = "%setfield0" external get : 'a Pervasives.ref -> 'a = "%field0" val copy : 'a Pervasives.ref -> 'a Pervasives.ref val pre : 'a Pervasives.ref -> ('a -> 'a) -> 'a val post : 'a Pervasives.ref -> ('a -> 'a) -> 'a val swap : 'a Pervasives.ref -> 'a Pervasives.ref -> unit val post_incr : int Pervasives.ref -> int val post_decr : int Pervasives.ref -> int val pre_incr : int Pervasives.ref -> int val pre_decr : int Pervasives.ref -> int val protect : 'a Pervasives.ref -> 'a -> (unit -> 'b) -> 'b val toggle : bool Pervasives.ref -> unit val oset : 'a option Pervasives.ref -> 'a -> unit val oget_exn : 'a option Pervasives.ref -> 'a val print : ('b BatInnerIO.output -> 'a -> unit) -> 'b BatInnerIO.output -> 'a BatRef.t -> unit val compare : 'a BatOrd.comp -> 'a Pervasives.ref BatOrd.comp val ord : 'a BatOrd.ord -> 'a Pervasives.ref BatOrd.ord val eq : 'a BatOrd.eq -> 'a Pervasives.ref BatOrd.eq end`