Batteries user guide : BatHashtbl.Labels

`sig
val add : ('a, 'b) BatHashtbl.t -> key:'a -> data:'b -> unit
val replace : ('a, 'b) BatHashtbl.t -> key:'a -> data:'b -> unit
val iter : f:(key:'a -> data:'b -> unit) -> ('a, 'b) BatHashtbl.t -> unit
val map :
f:(key:'a -> data:'b -> 'c) ->
('a, 'b) BatHashtbl.t -> ('a, 'c) BatHashtbl.t
val map_inplace :
f:(key:'a -> data:'b -> 'b) -> ('a, 'b) BatHashtbl.t -> unit
val filter :
f:('a -> bool) -> ('key, 'a) BatHashtbl.t -> ('key, 'a) BatHashtbl.t
val filter_inplace : f:('a -> bool) -> ('key, 'a) BatHashtbl.t -> unit
val filteri :
f:(key:'key -> data:'a -> bool) ->
('key, 'a) BatHashtbl.t -> ('key, 'a) BatHashtbl.t
val filteri_inplace :
f:(key:'key -> data:'a -> bool) -> ('key, 'a) BatHashtbl.t -> unit
val filter_map :
f:(key:'key -> data:'a -> 'b option) ->
('key, 'a) BatHashtbl.t -> ('key, 'b) BatHashtbl.t
val filter_map_inplace :
f:(key:'key -> data:'a -> 'a option) -> ('key, 'a) BatHashtbl.t -> unit
val fold :
f:(key:'a -> data:'b -> 'c -> 'c) ->
('a, 'b) BatHashtbl.t -> init:'c -> 'c
val modify : key:'a -> f:('b -> 'b) -> ('a, 'b) BatHashtbl.t -> unit
val modify_def :
default:'b -> key:'a -> f:('b -> 'b) -> ('a, 'b) BatHashtbl.t -> unit
val modify_opt :
key:'a -> f:('b option -> 'b option) -> ('a, 'b) BatHashtbl.t -> unit
end`