API / Belt / Set

Set

An immutable sorted set module which allows customized 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.

Examples

RESCRIPT
module PairComparator =
  Belt.Id.MakeComparable({
    type t = (int, int)
    let cmp = ((a0, a1), (b0, b1)) =>
      switch (Pervasives.compare(a0, b0)) {
      | 0 => Pervasives.compare(a1, b1)
      | c => c
      }
  })

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

Note: This module's examples will assume a predeclared module for integers called IntCmp. It is declared like this:

RESCRIPT
module IntCmp =
  Belt.Id.MakeComparable({
    type t = int
    let cmp = Pervasives.compare
  })

t

RESCRIPT
type t<'value, 'identity>

'value is the element type

'identity the identity of the collection

id

RESCRIPT
type id<'value, 'id> = Belt_Id.comparable<'value, 'id>

The identity needed for making a set from scratch

make

RESCRIPT
let make: (~id: id<'value, 'id>) => t<'value, 'id>

Creates a new set by taking in the comparator

Examples

RESCRIPT
let set = Belt.Set.make(~id=module(IntCmp))

fromArray

RESCRIPT
let fromArray: (array<'value>, ~id: id<'value, 'id>) => t<'value, 'id>

Creates new set from array of elements.

Examples

RESCRIPT
let s0 = Belt.Set.fromArray([1, 3, 2, 4], ~id=module(IntCmp))

s0->Belt.Set.toArray /* [1, 2, 3, 4] */

fromSortedArrayUnsafe

RESCRIPT
let fromSortedArrayUnsafe: (array<'value>, ~id: id<'value, 'id>) => t<'value, 'id>

The same as [fromArray][#fromarray] except it is after assuming the input array is already sorted.

isEmpty

RESCRIPT
let isEmpty: t<'a, 'b> => bool

Checks if set is empty.

Examples

RESCRIPT
let empty = Belt.Set.fromArray([], ~id=module(IntCmp))
let notEmpty = Belt.Set.fromArray([1],~id=module(IntCmp))

Belt.Set.isEmpty(empty) /* true */
Belt.Set.isEmpty(notEmpty) /* false */

has

RESCRIPT
let has: (t<'value, 'id>, 'value) => bool

Checks if element exists in set.

Examples

RESCRIPT
let set = Belt.Set.fromArray([1, 4, 2, 5], ~id=module(IntCmp))

set->Belt.Set.has(3) /* false */
set->Belt.Set.has(1) /* true */

add

RESCRIPT
let add: (t<'value, 'id>, 'value) => t<'value, 'id>

Adds element to set. If element existed in set, value is unchanged.

Examples

RESCRIPT
let s0 = Belt.Set.make(~id=module(IntCmp))
let s1 = s0->Belt.Set.add(1)
let s2 = s1->Belt.Set.add(2)
let s3 = s2->Belt.Set.add(2)
s0->Belt.Set.toArray /* [] */
s1->Belt.Set.toArray /* [1] */
s2->Belt.Set.toArray /* [1, 2] */
s3->Belt.Set.toArray /* [1,2 ] */
s2 == s3 /* true */

mergeMany

RESCRIPT
let mergeMany: (t<'value, 'id>, array<'value>) => t<'value, 'id>

Adds each element of array to set. Unlike Belt.Set.add](#add), the reference of return value might be changed even if all values in array already exist in set

Examples

RESCRIPT
let set = Belt.Set.make(~id=module(IntCmp))

let newSet = set->Belt.Set.mergeMany([5, 4, 3, 2, 1])
newSet->Belt.Set.toArray /* [1, 2, 3, 4, 5] */

remove

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

Removes element from set. If element did not exist in set, value is unchanged.

Examples

RESCRIPT
let s0 = Belt.Set.fromArray([2,3,1,4,5], ~id=module(IntCmp))
let s1 = s0->Belt.Set.remove(1)
let s2 = s1->Belt.Set.remove(3)
let s3 = s2->Belt.Set.remove(3)

s1->Belt.Set.toArray /* [2,3,4,5] */
s2->Belt.Set.toArray /* [2,4,5] */
s2 == s3 /* true */

removeMany

RESCRIPT
let removeMany: (t<'value, 'id>, array<'value>) => t<'value, 'id>

Removes each element of array from set. Unlike remove, the reference of return value might be changed even if none of values in array existed in set.

Examples

RESCRIPT
let set = Belt.Set.fromArray([1, 2, 3, 4],~id=module(IntCmp))

let newSet = set->Belt.Set.removeMany([5, 4, 3, 2, 1])
newSet->Belt.Set.toArray /* [] */

union

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

Returns union of two sets.

Examples

RESCRIPT
let s0 = Belt.Set.fromArray([5,2,3,5,6], ~id=module(IntCmp))
let s1 = Belt.Set.fromArray([5,2,3,1,5,4], ~id=module(IntCmp))
let union = Belt.Set.union(s0, s1)
union->Belt.Set.toArray /* [1,2,3,4,5,6] */

intersect

RESCRIPT
let intersect: (t<'value, 'id>, t<'value, 'id>) => t<'value, 'id>

Returns intersection of two sets.

Examples

RESCRIPT
let s0 = Belt.Set.fromArray([5,2,3,5,6], ~id=module(IntCmp))
let s1 = Belt.Set.fromArray([5,2,3,1,5,4], ~id=module(IntCmp))
let intersect = Belt.Set.intersect(s0, s1)
intersect->Belt.Set.toArray /* [2,3,5] */

diff

RESCRIPT
let diff: (t<'value, 'id>, t<'value, 'id>) => t<'value, 'id>

Returns elements from first set, not existing in second set.

Examples

RESCRIPT
let s0 = Belt.Set.fromArray([5,2,3,5,6], ~id=module(IntCmp))
let s1 = Belt.Set.fromArray([5,2,3,1,5,4], ~id=module(IntCmp))
Belt.Set.toArray(Belt.Set.diff(s0, s1)) /* [6] */
Belt.Set.toArray(Belt.Set.diff(s1,s0)) /* [1,4] */

subset

RESCRIPT
let subset: (t<'value, 'id>, t<'value, 'id>) => bool

Checks if second set is subset of first set.

Examples

RESCRIPT
let s0 = Belt.Set.fromArray([5,2,3,5,6], ~id=module(IntCmp))
let s1 = Belt.Set.fromArray([5,2,3,1,5,4], ~id=module(IntCmp))
let s2 = Belt.Set.intersect(s0, s1)
Belt.Set.subset(s2, s0) /* true */
Belt.Set.subset(s2, s1) /* true */
Belt.Set.subset(s1, s0) /* false */

cmp

RESCRIPT
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 compares size first and then iterates over each element following the order of elements.

eq

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

Checks if two sets are equal.

Examples

RESCRIPT
let s0 = Belt.Set.fromArray([5,2,3], ~id=module(IntCmp))
let s1 = Belt.Set.fromArray([3,2,5], ~id=module(IntCmp))

Belt.Set.eq(s0, s1) /* true */

forEachU

RESCRIPT
let forEachU: (t<'value, 'id>, 'value => unit) => unit

Same as forEach but takes uncurried functon.

forEach

RESCRIPT
let forEach: (t<'value, 'id>, 'value => unit) => unit

Applies function f in turn to all elements of set in increasing order.

Examples

RESCRIPT
let s0 = Belt.Set.fromArray([5,2,3,5,6], ~id=module(IntCmp))
let acc = ref(list{})
s0->Belt.Set.forEach(x => {
  acc := Belt.List.add(acc.contents, x)
})
acc /* [6,5,3,2] */

reduceU

RESCRIPT
let reduceU: (t<'value, 'id>, 'a, ('a, 'value) => 'a) => 'a

reduce

RESCRIPT
let reduce: (t<'value, 'id>, 'a, ('a, 'value) => 'a) => 'a

Applies function f to each element of set in increasing order. Function f has two parameters: the item from the set and an “accumulator”, which starts with a value of initialValue. reduce returns the final value of the accumulator.

Examples

RESCRIPT
let s0 = Belt.Set.fromArray([5,2,3,5,6], ~id=module(IntCmp))
s0->Belt.Set.reduce(list{}, (acc, element) =>
  acc->Belt.List.add(element)
) /* [6,5,3,2] */

everyU

RESCRIPT
let everyU: (t<'value, 'id>, 'value => bool) => bool

every

RESCRIPT
let every: (t<'value, 'id>, 'value => bool) => bool

Checks if all elements of the set satisfy the predicate. Order unspecified.

Examples

RESCRIPT
let isEven = x => mod(x, 2) == 0

let s0 = Belt.Set.fromArray([2,4,6,8], ~id=module(IntCmp))
s0->Belt.Set.every(isEven) /* true */

someU

RESCRIPT
let someU: (t<'value, 'id>, 'value => bool) => bool

some

RESCRIPT
let some: (t<'value, 'id>, 'value => bool) => bool

Checks if at least one element of the set satisfies the predicate.

Examples

RESCRIPT
let isOdd = x => mod(x, 2) != 0

let s0 = Belt.Set.fromArray([1,2,4,6,8], ~id=module(IntCmp))
s0->Belt.Set.some(isOdd) /* true */

keepU

RESCRIPT
let keepU: (t<'value, 'id>, 'value => bool) => t<'value, 'id>

keep

RESCRIPT
let keep: (t<'value, 'id>, 'value => bool) => t<'value, 'id>

Returns the set of all elements that satisfy the predicate.

Examples

RESCRIPT
let isEven = x => mod(x, 2) == 0

let s0 = Belt.Set.fromArray([1,2,3,4,5], ~id=module(IntCmp))
let s1 = s0->Belt.Set.keep(isEven)

s1->Belt.Set.toArray /* [2,4] */

partitionU

RESCRIPT
let partitionU: ( t<'value, 'id>, 'value => bool, ) => (t<'value, 'id>, t<'value, 'id>)

partition

RESCRIPT
let partition: ( t<'value, 'id>, 'value => bool, ) => (t<'value, 'id>, t<'value, 'id>)

Returns a pair of sets, where first is the set of all the elements of set that satisfy the predicate, and second is the set of all the elements of set that do not satisfy the predicate.

Examples

RESCRIPT
let isOdd = x => mod(x, 2) != 0

let s0 = Belt.Set.fromArray([1,2,3,4,5], ~id=module(IntCmp))
let (s1, s2) = s0->Belt.Set.partition(isOdd)

s1->Belt.Set.toArray /* [1,3,5] */
s2->Belt.Set.toArray /* [2,4] */

size

RESCRIPT
let size: t<'value, 'id> => int

Returns size of the set.

Examples

RESCRIPT
let s0 = Belt.Set.fromArray([1,2,3,4], ~id=module(IntCmp))

s0->Belt.Set.size /* 4 */

toArray

RESCRIPT
let toArray: t<'value, 'id> => array<'value>

Returns array of ordered set elements.

Examples

RESCRIPT
let s0 = Belt.Set.fromArray([3,2,1,5], ~id=module(IntCmp))

s0->Belt.Set.toArray /* [1,2,3,5] */

toList

RESCRIPT
let toList: t<'value, 'id> => list<'value>

Returns list of ordered set elements.

Examples

RESCRIPT
let s0 = Belt.Set.fromArray([3,2,1,5], ~id=module(IntCmp))

s0->Belt.Set.toList /* [1,2,3,5] */

minimum

RESCRIPT
let minimum: t<'value, 'id> => option<'value>

Returns minimum value of the collection. None if collection is empty.

Examples

RESCRIPT
let s0 = Belt.Set.make(~id=module(IntCmp))
let s1 = Belt.Set.fromArray([3,2,1,5], ~id=module(IntCmp))

s0->Belt.Set.minimum /* None */
s1->Belt.Set.minimum /* Some(1) */

minUndefined

RESCRIPT
let minUndefined: t<'value, 'id> => Js.undefined<'value>

Returns minimum value of the collection. undefined if collection is empty.

Examples

RESCRIPT
let s0 = Belt.Set.make(~id=module(IntCmp))
let s1 = Belt.Set.fromArray([3,2,1,5], ~id=module(IntCmp))

s0->Belt.Set.minUndefined /* undefined */
s1->Belt.Set.minUndefined /* 1 */

maximum

RESCRIPT
let maximum: t<'value, 'id> => option<'value>

Returns maximum value of the collection. None if collection is empty.

Examples

RESCRIPT
let s0 = Belt.Set.make(~id=module(IntCmp))
let s1 = Belt.Set.fromArray([3,2,1,5], ~id=module(IntCmp))

s0->Belt.Set.maximum /* None */
s1->Belt.Set.maximum /* Some(5) */

maxUndefined

RESCRIPT
let maxUndefined: t<'value, 'id> => Js.undefined<'value>

Returns maximum value of the collection. undefined if collection is empty.

Examples

RESCRIPT
let s0 = Belt.Set.make(~id=module(IntCmp))
let s1 = Belt.Set.fromArray([3,2,1,5], ~id=module(IntCmp))

s0->Belt.Set.maxUndefined /* undefined */
s1->Belt.Set.maxUndefined /* 5 */

get

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

Returns the reference of the value which is equivalent to value using the comparator specifiecd by this collection. Returns None if element does not exist.

Examples

RESCRIPT
let s0 = Belt.Set.fromArray([1,2,3,4,5], ~id=module(IntCmp))

s0->Belt.Set.get(3) /* Some(3) */
s0->Belt.Set.get(20) /* None */

getUndefined

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

Same as get but returns undefined when element does not exist.

getExn

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

Same as get but raise when element does not exist.

split

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

Returns a tuple ((smaller, larger), present), present is true when element exist in set.

Examples

RESCRIPT
let s0 = Belt.Set.fromArray([1,2,3,4,5], ~id=module(IntCmp))

let ((smaller, larger), present) = s0->Belt.Set.split(3)

present /* true */
smaller->Belt.Set.toArray /* [1,2] */
larger->Belt.Set.toArray /* [4,5] */

checkInvariantInternal

RESCRIPT
let checkInvariantInternal: t<'a, 'b> => unit

raise when invariant is not held

getData

RESCRIPT
let getData: t<'value, 'id> => Belt_SetDict.t<'value, 'id>

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.

getId

RESCRIPT
let getId: t<'value, 'id> => id<'value, 'id>

Advanced usage only

Returns the identity of set.

packIdData

RESCRIPT
let packIdData: ( ~id: id<'value, 'id>, ~data: Belt_SetDict.t<'value, 'id>, ) => t<'value, 'id>

Advanced usage only

Returns the packed collection.