effect-io-ai

Package: effect
Module: Option

Option.exists

Checks if a value in an Option satisfies a given predicate or refinement.

Details

This function allows you to check if a value inside a Some meets a specified condition. If the Option is None, the result is false. If the Option is Some, the provided predicate or refinement is applied to the value:

• If the condition is met, the result is true.
• If the condition is not met, the result is false.

Example

import { Option } from "effect"

const isEven = (n: number) => n % 2 === 0

console.log(Option.some(2).pipe(Option.exists(isEven)))
// Output: true

console.log(Option.some(1).pipe(Option.exists(isEven)))
// Output: false

console.log(Option.none().pipe(Option.exists(isEven)))
// Output: false

Signature

declare const exists: { <A, B extends A>(refinement: Refinement<NoInfer<A>, B>): (self: Option<A>) => self is Option<B>; <A>(predicate: Predicate<NoInfer<A>>): (self: Option<A>) => boolean; <A, B extends A>(self: Option<A>, refinement: Refinement<A, B>): self is Option<B>; <A>(self: Option<A>, predicate: Predicate<A>): boolean; }

Source

Since v2.0.0