Module Belt.HashSet

Belt.HashSet

The top level provides generic mutable hash set operations.

It also has two specialized inner modules Belt.HashSet.Int and Belt.HashSet.String

A mutable Hash set which allows customized hash behavior.

All data are parameterized by not its only type but also a unique identity in the time of initialization, so that two HashSets of ints initialized with different hash functions will have different type.

For example:

  type t = int
  module I0 =
    (val Belt.Id.hashableU
        ~hash:(fun[\@u] (a : t)  -> a & 0xff_ff)
        ~eq:(fun[\@u] a b -> a = b)
    )
  let s0 = make ~id:(module I0) ~hintSize:40
  module I1 =
    (val Belt.Id.hashableU
        ~hash:(fun[\@u] (a : t)  -> a & 0xff)
        ~eq:(fun[\@u] a b -> a = b)
    )
  let s1 = make ~id:(module I1) ~hintSize:40

The invariant must be held: for two elements who are equal, their hashed value should be the same

Here the compiler would infer s0 and s1 having different type so that it would not mix.

  val s0 :  (int, I0.identity) t
  val s1 :  (int, I1.identity) t

external s0: t(int, I0.identity) = ;
external s1: t(int, I1.identity) = ;

We can add elements to the collection:

  let () =
    add s1 0;
    add s1 1

let () = {
  add(s1, 0);
  add(s1, 1);
};

Since this is an mutable data strucure, s1 will contain two pairs.

module Int : sig ... end

module Int: { ... };

Specalized when key type is int, more efficient than the generic type

module String : sig ... end

module String: { ... };

Specalized when key type is string, more efficient than the generic type

type ('a, 'id) t

type t('a, 'id);

The type of hash tables from type 'a to type 'b.

type ('a, 'id) id =
  (module Belt__.Belt_Id.Hashable
  with type identity = 'id
   and type t = 'a)

type id('a, 'id) =
  (module Belt__.Belt_Id.Hashable
  with type identity = 'id
   and type t = 'a);

val make : hintSize:int -> id:('a, 'id) id -> ('a, 'id) t

let make: hintSize:int => id:id('a, 'id) => t('a, 'id);

val clear : ('a, 'id) t -> unit

let clear: t('a, 'id) => unit;

val isEmpty : (_, _) t -> bool

let isEmpty: t(_, _) => bool;

val add : ('a, 'id) t -> 'a -> unit

let add: t('a, 'id) => 'a => unit;

val copy : ('a, 'id) t -> ('a, 'id) t

let copy: t('a, 'id) => t('a, 'id);

val has : ('a, 'id) t -> 'a -> bool

let has: t('a, 'id) => 'a => bool;

val remove : ('a, 'id) t -> 'a -> unit

let remove: t('a, 'id) => 'a => unit;

val forEachU : ('a, 'id) t -> ('a -> unit) Js.Fn.arity1 -> unit

let forEachU: t('a, 'id) => Js.Fn.arity1(('a => unit)) => unit;

val forEach : ('a, 'id) t -> ('a -> unit) -> unit

let forEach: t('a, 'id) => ('a => unit) => unit;

Order unspecified.

val reduceU : ('a, 'id) t -> 'c -> ('c -> 'a -> 'c) Js.Fn.arity2 -> 'c

let reduceU: t('a, 'id) => 'c => Js.Fn.arity2(('c => 'a => 'c)) => 'c;

val reduce : ('a, 'id) t -> 'c -> ('c -> 'a -> 'c) -> 'c

let reduce: t('a, 'id) => 'c => ('c => 'a => 'c) => 'c;

Order unspecified.

val size : ('a, 'id) t -> int

let size: t('a, 'id) => int;

val logStats : (_, _) t -> unit

let logStats: t(_, _) => unit;

val toArray : ('a, 'id) t -> 'a array

let toArray: t('a, 'id) => array('a);

val fromArray : 'a array -> id:('a, 'id) id -> ('a, 'id) t

let fromArray: array('a) => id:id('a, 'id) => t('a, 'id);

val mergeMany : ('a, 'id) t -> 'a array -> unit

let mergeMany: t('a, 'id) => array('a) => unit;

val getBucketHistogram : (_, _) t -> int array

let getBucketHistogram: t(_, _) => array(int);