effect-io-ai

Package: effect
Module: Iterable

Iterable.headUnsafe

Gets the first element of an Iterable without returning an Option.

When to use

Use when the Iterable is known to be non-empty and direct access to the first element is preferred over handling Option.none.

Gotchas

Throws if the Iterable is empty.

Example (Getting the first element unsafely)

import { Iterable } from "effect"

const numbers = [1, 2, 3]
console.log(Iterable.headUnsafe(numbers)) // 1

const letters = "hello"
console.log(Iterable.headUnsafe(letters)) // "h"

// Iterable.headUnsafe(Iterable.empty<number>())
// throws Error: "headUnsafe: empty iterable"

// Use only when you're certain the iterable is non-empty
const nonEmpty = Iterable.range(1, 10)
console.log(Iterable.headUnsafe(nonEmpty)) // 1

Signature

declare const headUnsafe: <A>(self: Iterable<A>) => A

Source

Since v4.0.0