effect-io-ai

Package: effect
Module: Either

Either.isLeft

Determine if a Either is a Left.

Example

import * as assert from "node:assert"
import { Either } from "effect"

assert.deepStrictEqual(Either.isLeft(Either.right(1)), false)
assert.deepStrictEqual(Either.isLeft(Either.left("a")), true)

Signature

declare const isLeft: <A, E>(self: Either<A, E>) => self is Left<E, A>

Source

Since v2.0.0