effect-io-ai

Package: effect
Module: Result

Result.liftPredicate

Lifts a value into a Result based on a predicate or refinement.

When to use

Use to construct a Result from a raw value guarded by a predicate or refinement.

Details

• If the predicate returns true, the value becomes Success<A>
• If the predicate returns false, orFailWith produces the error for Failure<E>
• Also accepts a Refinement to narrow the success type
• Supports both data-first and data-last (piped) usage

Example (Validating a number)

import { pipe, Result } from "effect"

const ensurePositive = pipe(
  5,
  Result.liftPredicate(
    (n: number) => n > 0,
    (n) => `${n} is not positive`
  )
)
console.log(ensurePositive)
// Output: { _tag: "Success", success: 5, ... }

See

• filterOrFail to validate a value that is already in a Result
• fromNullishOr for nullable-based construction

Signature

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

Source

Since v3.4.0