Module Belt.Set

Belt.Set

The top level provides generic immutable set operations.

It also has three specialized inner modules Belt.Set.Int, Belt.Set.String and

Belt.Set.Dict: This module separates data from function which is more verbose but slightly more efficient

A immutable sorted set module which allows customize compare behavior.

The implementation uses balanced binary trees, and therefore searching and insertion take time logarithmic in the size of the map.

For more info on this module's usage of identity, `make` and others, please see the top level documentation of Belt, A special encoding for collection safety.

Example usage:

module PairComparator = Belt.Id.MakeComparable(struct
  type t = int * int
  let cmp (a0, a1) (b0, b1) =
    match Pervasives.compare a0 b0 with
    | 0 -> Pervasives.compare a1 b1
    | c -> c
end)

let mySet = Belt.Set.make ~id:(module PairComparator)
let mySet2 = Belt.Set.add mySet (1, 2)

The API documentation below will assume a predeclared comparator module for integers, IntCmp

module Int: { ... };

Specalized when value type is int, more efficient than the generic type, its compare behavior is fixed using the built-in comparison

module String: { ... };

Specalized when value type is string, more efficient than the generic type, its compare behavior is fixed using the built-in comparison

module Dict: { ... };

This module seprate identity from data, it is a bit more verboe but slightly more efficient due to the fact that there is no need to pack identity and data back after each operation

type t('value, 'identity);

('value, 'identity) t

'value is the element type

'identity the identity of the collection

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

The identity needed for making a set from scratch

let make: id:id('value, 'id) => t('value, 'id);

make ~id creates a new set by taking in the comparator

let s = make ~id:(module IntCmp)
let fromArray: array('value) => id:id('value, 'id) => t('value, 'id);

fromArray xs ~id

toArray (fromArray [1;3;2;4] (module IntCmp)) = [1;2;3;4]
let fromSortedArrayUnsafe: array('value) => id:id('value, 'id) => t('value, 'id);

fromSortedArrayUnsafe xs ~id

The same as fromArray except it is after assuming the input array x is already sorted

Unsafe

let isEmpty: t(_, _) => bool;
isEmpty (fromArray [||] ~id:(module IntCmp)) = true;;
isEmpty (fromArray [|1|] ~id:(module IntCmp)) = true;;
let has: t('value, 'id) => 'value => bool;
let v = fromArray [|1;4;2;5|] ~id:(module IntCmp);;
has v 3 = false;;
has v 1 = true;;
let add: t('value, 'id) => 'value => t('value, 'id);

add s x If x was already in s, s is returned unchanged.

let s0 = make ~id:(module IntCmp);;
let s1 = add s0 1 ;;
let s2 = add s1 2;;
let s3 = add s2 2;;
toArray s0 = [||];;
toArray s1 = [|1|];;
toArray s2 = [|1;2|];;
toArray s3 = [|1;2|];;
s2 == s3;;
let mergeMany: t('value, 'id) => array('value) => t('value, 'id);

mergeMany s xs

Adding each of xs to s, note unlike add, the reference of return value might be changed even if all values in xs exist s

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

remove m x If x was not in m, m is returned reference unchanged.

let s0 = fromArray ~id:(module IntCmp) [|2;3;1;4;5|];;
let s1 = remove s0 1 ;;
let s2 = remove s1 3 ;;
let s3 = remove s2 3 ;;

toArray s1 = [|2;3;4;5|];;
toArray s2 = [|2;4;5|];;
s2 == s3;;
let removeMany: t('value, 'id) => array('value) => t('value, 'id);

removeMany s xs

Removing each of xs to s, note unlike remove, the reference of return value might be changed even if none in xs exists s

let union: t('value, 'id) => t('value, 'id) => t('value, 'id);

union s0 s1

let s0 = fromArray ~id:(module IntCmp) [|5;2;3;5;6|]];;
let s1 = fromArray ~id:(module IntCmp) [|5;2;3;1;5;4;|];;
toArray (union s0 s1) =  [|1;2;3;4;5;6|]
let intersect: t('value, 'id) => t('value, 'id) => t('value, 'id);

intersect s0 s1

let s0 = fromArray ~id:(module IntCmp) [|5;2;3;5;6|]];;
let s1 = fromArray ~id:(module IntCmp) [|5;2;3;1;5;4;|];;
toArray (intersect s0 s1) =  [|2;3;5|]
let diff: t('value, 'id) => t('value, 'id) => t('value, 'id);

diff s0 s1

let s0 = fromArray ~id:(module IntCmp) [|5;2;3;5;6|]];;
let s1 = fromArray ~id:(module IntCmp) [|5;2;3;1;5;4;|];;
toArray (diff s0 s1) = [|6|];;
toArray (diff s1 s0) = [|1;4|];;
let subset: t('value, 'id) => t('value, 'id) => bool;

subset s0 s1

let s0 = fromArray ~id:(module IntCmp) [|5;2;3;5;6|]];;
let s1 = fromArray ~id:(module IntCmp) [|5;2;3;1;5;4;|];;
let s2 = intersect s0 s1;;
subset s2 s0 = true;;
subset s2 s1 = true;;
subset s1 s0 = false;;
let cmp: t('value, 'id) => t('value, 'id) => int;

Total ordering between sets. Can be used as the ordering function for doing sets of sets. It compare size first and then iterate over each element following the order of elements

let eq: t('value, 'id) => t('value, 'id) => bool;

eq s0 s1

  • returns

    true if toArray s0 = toArray s1

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

forEach s f applies f in turn to all elements of s. In increasing order

let s0 = fromArray ~id:(module IntCmp) [|5;2;3;5;6|]];;
let acc = ref [] ;;
forEach s0 (fun x -> acc := x !acc);;
!acc = [6;5;3;2];;
let reduceU: t('value, 'id) => 'a => Js.Fn.arity2(('a => 'value => 'a)) => 'a;
let reduce: t('value, 'id) => 'a => ('a => 'value => 'a) => 'a;

In increasing order.

let s0 = fromArray ~id:(module IntCmp) [|5;2;3;5;6|]];;
reduce s0 [] Bs.List.add = [6;5;3;2];;
let everyU: t('value, 'id) => Js.Fn.arity1(('value => bool)) => bool;
let every: t('value, 'id) => ('value => bool) => bool;

every p s checks if all elements of the set satisfy the predicate p. Order unspecified.

let someU: t('value, 'id) => Js.Fn.arity1(('value => bool)) => bool;
let some: t('value, 'id) => ('value => bool) => bool;

some p s checks if at least one element of the set satisfies the predicate p.

let keepU: t('value, 'id) => Js.Fn.arity1(('value => bool)) => t('value, 'id);
let keep: t('value, 'id) => ('value => bool) => t('value, 'id);

keep m p returns the set of all elements in s that satisfy predicate p.

let partitionU: t('value, 'id) => Js.Fn.arity1(('value => bool)) => (t('value, 'id), t('value, 'id));
let partition: t('value, 'id) => ('value => bool) => (t('value, 'id), t('value, 'id));

partition m p returns a pair of sets (s1, s2), where s1 is the set of all the elements of s that satisfy the predicate p, and s2 is the set of all the elements of s that do not satisfy p.

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

size s

let s0 = fromArray ~id:(module IntCmp) [|5;2;3;5;6|]];;
size s0 = 4;;
let toArray: t('value, 'id) => array('value);

toArray s0

let s0 = fromArray ~id:(module IntCmp) [|5;2;3;5;6|]];;
toArray s0 = [|2;3;5;6|];;
let toList: t('value, 'id) => list('value);

In increasing order

See toArray

let minimum: t('value, 'id) => option('value);

minimum s0

  • returns

    the minimum element of the collection, None if it is empty

let minUndefined: t('value, 'id) => Js.undefined('value);

minUndefined s0

  • returns

    the minimum element of the collection, undefined if it is empty

let maximum: t('value, 'id) => option('value);

maximum s0

  • returns

    the maximum element of the collection, None if it is empty

let maxUndefined: t('value, 'id) => Js.undefined('value);

maxUndefined s0

  • returns

    the maximum element of the collection, undefined if it is empty

let get: t('value, 'id) => 'value => option('value);

get s0 k

  • returns

    the reference of the value k' which is equivalent to k using the comparator specifiecd by this collection, None if it does not exist

let getUndefined: t('value, 'id) => 'value => Js.undefined('value);

See get

let getExn: t('value, 'id) => 'value => 'value;

See get

raise if not exist

let split: t('value, 'id) => 'value => ((t('value, 'id), t('value, 'id)), bool);

split set ele

  • returns

    a tuple ((smaller, larger), present), present is true when ele exist in set

Below are operations only when better performance needed, it is still safe API but more verbose. More API will be exposed by needs

let getData: t('value, 'id) => Belt__.Belt_SetDict.t('value, 'id);

getData s0

Advanced usage only

  • returns

    the raw data (detached from comparator), but its type is still manifested, so that user can pass identity directly without boxing

let getId: t('value, 'id) => id('value, 'id);

getId s0

Advanced usage only

  • returns

    the identity of s0

let packIdData: id:id('value, 'id) => data:Belt__.Belt_SetDict.t('value, 'id) => t('value, 'id);

packIdData ~id ~data

Advanced usage only

  • returns

    the packed collection