effect-io-ai

Package: effect
Module: Result

Result.filterOrFail

Validates the success value of a Result using a predicate, failing with a custom error if the predicate returns false.

When to use

Use to validate an already-successful Result value with a predicate or refinement.

Details

• If the result is already a Failure, it is returned as-is
• If the predicate passes, the Success is returned unchanged
• If the predicate fails, orFailWith produces the error for a new Failure
• Also accepts a Refinement to narrow the success type
• The error type of the output is the union of both error types

Example (Filtering a success value)

import { pipe, Result } from "effect"

const result = pipe(
  Result.succeed(0),
  Result.filterOrFail(
    (n) => n > 0,
    (n) => `${n} is not positive`
  )
)
console.log(result)
// Output: { _tag: "Failure", failure: "0 is not positive", ... }

See

• liftPredicate to create a Result from a raw value with a predicate
• flatMap for general conditional chaining

Signature

declare const filterOrFail: { <A, B extends A, E2>(refinement: Refinement<NoInfer<A>, B>, orFailWith: (value: NoInfer<A>) => E2): <E>(self: Result<A, E>) => Result<B, E2 | E>; <A, E2>(predicate: Predicate<NoInfer<A>>, orFailWith: (value: NoInfer<A>) => E2): <E>(self: Result<A, E>) => Result<A, E2 | E>; <A, E, B extends A, E2>(self: Result<A, E>, refinement: Refinement<A, B>, orFailWith: (value: A) => E2): Result<B, E | E2>; <A, E, E2>(self: Result<A, E>, predicate: Predicate<A>, orFailWith: (value: A) => E2): Result<A, E | E2>; }

Source

Since v4.0.0