effect-io-ai

Package: effect
Module: Option

Option.liftPredicate

Lifts a Predicate or Refinement into the Option context: returns Some(value) when the predicate holds, None otherwise.

When to use

Use to convert a boolean check into an Option-returning function

• Validating input and wrapping it in Option

Details

• predicate(value) is true → Some(value)
• predicate(value) is false → None
• Supports refinements for type narrowing

Example (Validating positive numbers)

import { Option } from "effect"

const parsePositive = Option.liftPredicate((n: number) => n > 0)

console.log(parsePositive(1))
// Output: { _id: 'Option', _tag: 'Some', value: 1 }

console.log(parsePositive(-1))
// Output: { _id: 'Option', _tag: 'None' }

See

• filter to apply a predicate to an existing Option
• toRefinement for the inverse direction

Signature

declare const liftPredicate: { <A, B extends A>(refinement: Refinement<A, B>): (a: A) => Option<B>; <B extends A, A = B>(predicate: Predicate<A>): (b: B) => Option<B>; <A, B extends A>(self: A, refinement: Refinement<A, B>): Option<B>; <B extends A, A = B>(self: B, predicate: Predicate<A>): Option<B>; }

Source

Since v2.0.0