containers
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package containers
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Extension to the standard Hashtbl

  • since 0.4
type 'a sequence = ('a -> unit) -> unit
type 'a eq = 'a -> 'a -> bool
type 'a hash = 'a -> int
type 'a printer = Format.formatter -> 'a -> unit

Polymorphic tables

This sub-module contains the extension of the standard polymorphic Hashtbl.

module Poly : sig ... end
include module type of Poly
val get : ('a, 'b) Hashtbl.t -> 'a -> 'b option

Safe version of Hashtbl.find.

val get_or : ('a, 'b) Hashtbl.t -> 'a -> default:'b -> 'b

get_or tbl k ~default returns the value associated to k if present, and returns default otherwise (if k doesn't belong in tbl).

  • since 0.16
val keys : ('a, 'b) Hashtbl.t -> 'a sequence

Iterate on keys (similar order as Hashtbl.iter).

val values : ('a, 'b) Hashtbl.t -> 'b sequence

Iterate on values in the table.

val keys_list : ('a, 'b) Hashtbl.t -> 'a list

keys_list t is the list of keys in t. If the key is in the Hashtable multiple times, all occurrences will be returned.

  • since 0.8
val values_list : ('a, 'b) Hashtbl.t -> 'b list

values_list t is the list of values in t.

  • since 0.8
val map_list : ('a -> 'b -> 'c) -> ('a, 'b) Hashtbl.t -> 'c list

Map on a hashtable's items, collect into a list.

val incr : ?by:int -> ('a, int) Hashtbl.t -> 'a -> unit

incr ?by tbl x increments or initializes the counter associated with x. If get tbl x = None, then after update, get tbl x = Some 1; otherwise, if get tbl x = Some n, now get tbl x = Some (n+1).

  • parameter by

    if specified, the int value is incremented by by rather than 1.

  • since 0.16
val decr : ?by:int -> ('a, int) Hashtbl.t -> 'a -> unit

Like incr but subtract 1 (or the value of by). If the value reaches 0, the key is removed from the table. This does nothing if the key is not already present in the table.

  • since 0.16
val to_seq : ('a, 'b) Hashtbl.t -> ('a * 'b) sequence

Iterate on bindings in the table.

val add_list : ('a, 'b list) Hashtbl.t -> 'a -> 'b -> unit

add_list tbl x y adds y to the list x is bound to. If x is not bound, it becomes bound to y.

  • since 0.16
val add_seq : ('a, 'b) Hashtbl.t -> ('a * 'b) sequence -> unit

Add the corresponding pairs to the table, using Hashtbl.add.

  • since 0.16
val of_seq : ('a * 'b) sequence -> ('a, 'b) Hashtbl.t

From the given bindings, added in order.

val add_seq_count : ('a, int) Hashtbl.t -> 'a sequence -> unit

add_seq_count tbl seq increments the count of each element of seq by calling incr. This is useful for counting how many times each element of seq occurs.

  • since 0.16
val of_seq_count : 'a sequence -> ('a, int) Hashtbl.t

Like add_seq_count, but allocates a new table and returns it.

  • since 0.16
val to_list : ('a, 'b) Hashtbl.t -> ('a * 'b) list

List of bindings (order unspecified).

val of_list : ('a * 'b) list -> ('a, 'b) Hashtbl.t

Build a table from the given list of bindings k_i -> v_i, added in order using add. If a key occurs several times, it will be added several times, and the visible binding will be the last one.

val update : ('a, 'b) Hashtbl.t -> f:('a -> 'b option -> 'b option) -> k:'a -> unit

update tbl ~f ~k updates key k by calling f k (Some v) if k was mapped to v, or f k None otherwise; if the call returns None then k is removed/stays removed, if the call returns Some v' then the binding k -> v' is inserted using Hashtbl.replace.

  • since 0.14
val get_or_add : ('a, 'b) Hashtbl.t -> f:('a -> 'b) -> k:'a -> 'b

get_or_add tbl ~k ~f finds and returns the binding of k in tbl, if it exists. If it does not exist, then f k is called to obtain a new binding v; k -> v is added to tbl and v is returned.

  • since 1.0
val pp : 'a printer -> 'b printer -> ('a, 'b) Hashtbl.t printer

Printer for table. Renamed from print since 2.0.

  • since 0.13

Functor

module type S = sig ... end
module Make (X : Hashtbl.HashedType) : S with type key = X.t and type 'a t = 'a Hashtbl.Make(X).t