API / Core / Set

Set

t

RESCRIPT
type t<'a> = Js.Set.t<'a>

Type representing an instance of Set.

make

RESCRIPT
let make: unit => t<'a>

Creates a new, mutable JavaScript Set. A Set is a collection of unique values.

See Set on MDN.

Examples

RESCRIPT
// You can annotate the type of your set if you want to let mySet: Set.t<string> = Set.make() // Or you can let ReScript infer what's in your Set let set = Set.make() set->Set.add("Fine name") // Inferred as Set.t<string>

Alternatives

A JavaScript Set is mutable. If you're looking for an immutable alternative, check out Belt.Set.

fromArray

RESCRIPT
let fromArray: array<'a> => t<'a>

Turns an array of values into a Set. Meaning only unique values are preserved.

Examples

RESCRIPT
type languages = ReScript | JavaScript | TypeScript let languageRank = [ReScript, JavaScript, TypeScript] let set = Set.fromArray(languageRank) // Set.t<languages> switch set->Set.has(ReScript) { | true => Console.log("Yay, ReScript is in there!") | false => Console.log("Uh-oh, something is _terribly_ wrong with this program... abort.") }

fromIterator

RESCRIPT
let fromIterator: Core__Iterator.t<'a> => t<'a>

Turns an iterator into a Set.

Examples

RESCRIPT
// Let's pretend we have an interator @val external someIterator: Iterator.t<int> = "someIterator" let set = Set.fromIterator(someIterator) // Set.t<int>

size

RESCRIPT
let size: t<'a> => int

Returns the size, the number of unique values, of the set.

Examples

RESCRIPT
let set = Set.make() set->Set.add("someValue") set->Set.add("someValue") set->Set.add("someValue2") let size = set->Set.size // 2

clear

RESCRIPT
let clear: t<'a> => unit

Clears all entries in the set.

Examples

RESCRIPT
let set = Set.make() set->Set.add("someKey") let size = set->Set.size // 1 set->Set.clear let size = set->Set.size // 0

add

RESCRIPT
let add: (t<'a>, 'a) => unit

Adds a new value to the set.

Examples

RESCRIPT
let set = Set.make() set->Set.add("someValue")

delete

RESCRIPT
let delete: (t<'a>, 'a) => bool

Deletes the provided value from the set. Returns a bool for whether the value existed, and was deleted.

Examples

RESCRIPT
let set = Set.make() set->Set.add("someValue") let didDeleteValue = set->Set.delete("someValue") Console.log(didDeleteValue) // Logs `true` to the console, becuase the set had the value, so it was successfully deleted let didDeleteValue = set->Set.delete("someNonExistantKey") Console.log(didDeleteValue) // Logs `false` to the console, becuase the value did not exist in the set

has

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

Checks whether the set has a specific value.

Examples

RESCRIPT
let set = Set.make() set->Set.add("someValue") switch set->Set.has("someValue") { | false => Console.log("Nope, didn't have it.") | true => Console.log("Yay, we have the value!") }

forEach

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

Iterates through all values of the set.

Examples

RESCRIPT
let set = Set.make() set->Set.add("someValue") set->Set.add("someValue2") set->Set.forEach(value => { Console.log(value) })

values

RESCRIPT
let values: t<'a> => Core__Iterator.t<'a>

Returns an iterator that holds all values of the set.

Examples

RESCRIPT
let set = Set.make() set->Set.add("someValue") set->Set.add("anotherValue") let values = set->Set.values // Logs the first value Console.log(Iterator.next(values).value) // You can also turn the iterator into an array. // Remember that an iterator consumes values. We'll need a fresh values iterator to get an array of all values, since we consumed a value via `next` above already. Console.log(set->Set.values->Iterator.toArray)