API / Core / Iterator

Iterator

Bindings to JavaScript iterators.

See iterator protocols on MDN.

t

RESCRIPT

type t<'a>

The type representing an iterator.

value

RESCRIPT

type value<'a> = {done: bool, value: option<'a>}

The current value of an iterator.

RESCRIPT

let next: t<'a> => value<'a>

Returns the next value of the iterator, if any.

See iterator protocols on MDN.

Examples

RESCRIPT
@val external someIterator: Iterator.t<int> = "someIterator"

// Pulls out the next value of the iterator
let {Iterator.done, value} = someIterator->Iterator.next

toArray

RESCRIPT

let toArray: t<'a> => array<'a>

Turns an iterator into an array of the remaining values. Remember that each invocation of next of an iterator consumes a value. Iterator.toArray will consume all remaining values of the iterator and return them in an array to you.

See iterator protocols on MDN.

Examples

RESCRIPT
let map = Map.make()
map->Map.set("someKey", "someValue")
map->Map.set("someKey2", "someValue2")

// `Map.keys` returns all keys of the map as an iterator.
let mapKeysAsArray = map->Map.keys->Iterator.toArray

Console.log(mapKeysAsArray) // Logs ["someKey", "someKey2"] to the console.

toArrayWithMapper

RESCRIPT

let toArrayWithMapper: (t<'a>, 'a => 'b) => array<'b>

toArray(iterator) turns iterator into an array of its remaining values, applying the provided mapper function on each item. Remember that each invocation of next of an iterator consumes a value. Iterator.toArrayWithMapper will consume all remaining values of the iterator and return them in an array to you.

See iterator protocols on MDN.

Examples

RESCRIPT
let map = Map.make()
map->Map.set("someKey", "someValue")
map->Map.set("someKey2", "someValue2")

// `Map.keys` returns all keys of the map as an iterator.
let mapKeysAsArray = map
  ->Map.keys
  ->Iterator.toArrayWithMapper(key => key->String.length)

Console.log(mapKeysAsArray) // Logs [7, 8] to the console.

forEach

RESCRIPT

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

forEach(iterator, fn) consumes all values in the iterator and runs the callback fn for each value.

See iterator protocols on MDN.

Examples

RESCRIPT
@val external someIterator: Iterator.t<int> = "someIterator"

someIterator->Iterator.forEach(value =>
  switch value {
  | Some(value) if value > 10 => Console.log("More than 10!")
  | _ => ()
  }
)