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 : sig ... end

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

module String : sig ... end

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

module Dict : sig ... end

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 ('value, 'identity) t

('value, 'identity) t

'value is the element type

'identity the identity of the collection

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

The identity needed for making a set from scratch

val make : id:('value, 'id) id -> ('value, 'id) t

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

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

fromArray xs ~id

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

fromSortedArrayUnsafe xs ~id

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

Unsafe

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

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;;
val mergeMany : ('value, 'id) t -> 'value array -> ('value, 'id) t

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

val remove : ('value, 'id) t -> 'value -> ('value, 'id) t

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;;
val removeMany : ('value, 'id) t -> 'value array -> ('value, 'id) t

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

val union : ('value, 'id) t -> ('value, 'id) t -> ('value, 'id) t

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|]
val intersect : ('value, 'id) t -> ('value, 'id) t -> ('value, 'id) t

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|]
val diff : ('value, 'id) t -> ('value, 'id) t -> ('value, 'id) t

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|];;
val subset : ('value, 'id) t -> ('value, 'id) t -> 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;;
val cmp : ('value, 'id) t -> ('value, 'id) t -> 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

val eq : ('value, 'id) t -> ('value, 'id) t -> bool

eq s0 s1

  • returns

    true if toArray s0 = toArray s1

val forEachU : ('value, 'id) t -> ('value -> unit) Js.Fn.arity1 -> unit
val forEach : ('value, 'id) t -> ('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];;
val reduceU : ('value, 'id) t -> 'a -> ('a -> 'value -> 'a) Js.Fn.arity2 -> 'a
val reduce : ('value, 'id) t -> 'a -> ('a -> 'value -> 'a) -> 'a

In increasing order.

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

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

val someU : ('value, 'id) t -> ('value -> bool) Js.Fn.arity1 -> bool
val some : ('value, 'id) t -> ('value -> bool) -> bool

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

val keepU : ('value, 'id) t -> ('value -> bool) Js.Fn.arity1 -> ('value, 'id) t
val keep : ('value, 'id) t -> ('value -> bool) -> ('value, 'id) t

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

val partitionU : ('value, 'id) t -> ('value -> bool) Js.Fn.arity1 -> ('value, 'id) t * ('value, 'id) t
val partition : ('value, 'id) t -> ('value -> bool) -> ('value, 'id) t * ('value, 'id) t

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.

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

size s

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

toArray s0

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

In increasing order

See toArray

val minimum : ('value, 'id) t -> 'value option

minimum s0

  • returns

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

val minUndefined : ('value, 'id) t -> 'value Js.undefined

minUndefined s0

  • returns

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

val maximum : ('value, 'id) t -> 'value option

maximum s0

  • returns

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

val maxUndefined : ('value, 'id) t -> 'value Js.undefined

maxUndefined s0

  • returns

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

val get : ('value, 'id) t -> 'value -> 'value option

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

val getUndefined : ('value, 'id) t -> 'value -> 'value Js.undefined

See get

val getExn : ('value, 'id) t -> 'value -> 'value

See get

raise if not exist

val split : ('value, 'id) t -> 'value -> (('value, 'id) t * ('value, 'id) t) * 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

val getData : ('value, 'id) t -> ('value, 'id) Belt__.Belt_SetDict.t

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

val getId : ('value, 'id) t -> ('value, 'id) id

getId s0

Advanced usage only

  • returns

    the identity of s0

val packIdData : id:('value, 'id) id -> data:('value, 'id) Belt__.Belt_SetDict.t -> ('value, 'id) t

packIdData ~id ~data

Advanced usage only

  • returns

    the packed collection