# Module type Hashtbl.S

    module type S = sig .. end

The output signature of the functor `Hashtbl.Make`.

    type key

    type 'a t

    val create : int -> 'a t

    val clear : 'a t -> unit

    val reset : 'a t -> unit

- Since 4.00.0

    val copy : 'a t -> 'a t

    val add : 'a t -> key -> 'a -> unit

    val remove : 'a t -> key -> unit

    val find : 'a t -> key -> 'a

    val find_opt : 'a t -> key -> 'a option

- Since 4.05.0

    val find_all : 'a t -> key -> 'a list

    val replace : 'a t -> key -> 'a -> unit

    val mem : 'a t -> key -> bool

    val iter : (key -> 'a -> unit) -> 'a t -> unit

    val filter_map_inplace : (key -> 'a -> 'a option) -> 'a t -> unit

- Since 4.03.0

    val fold : (key -> 'a -> 'b -> 'b) -> 'a t -> 'b -> 'b

    val length : 'a t -> int

    val stats : 'a t -> Hashtbl.statistics

- Since 4.00.0