Iterable.take — API

Iterable.takeconsteffect/Iterable.ts:586

(n: number): <A>(self: Iterable<A>) => Iterable<A>
<A>(self: Iterable<A>, n: number): Iterable<A>

Keeps only a max number of elements from the start of an Iterable, creating a new Iterable.

Details

n is normalized to a non-negative integer.

Example (Taking from the start)

import { Iterable } from "effect"

const numbers = [1, 2, 3, 4, 5]
const firstThree = Iterable.take(numbers, 3)
console.log(Array.from(firstThree)) // [1, 2, 3]

// Taking more than available returns all elements
const firstTen = Iterable.take(numbers, 10)
console.log(Array.from(firstTen)) // [1, 2, 3, 4, 5]

// Taking 0 or negative returns empty
const none = Iterable.take(numbers, 0)
console.log(Array.from(none)) // []

// Useful with infinite iterables
const naturals = Iterable.range(1)
const firstFive = Iterable.take(naturals, 5)
console.log(Array.from(firstFive)) // [1, 2, 3, 4, 5]

getters

Source effect/Iterable.ts:58618 lines

export const take: {
  (n: number): <A>(self: Iterable<A>) => Iterable<A>
  <A>(self: Iterable<A>, n: number): Iterable<A>
} = dual(2, <A>(self: Iterable<A>, n: number): Iterable<A> => ({
  [Symbol.iterator]() {
    let i = 0
    const iterator = self[Symbol.iterator]()
    return {
      next() {
        if (i < n) {
          i++
          return iterator.next()
        }
        return { done: true, value: undefined }
      }
    }
  }
}))