effect-io-ai

Package: effect
Module: Effect

Effect.orElseFail

Replaces the failure of an effect with a custom failure value.

Details

This function allows you to handle the failure of an effect by replacing it with a predefined failure value. If the effect fails, the new failure value provided by the evaluate function will be returned instead of the original failure. If the effect succeeds, the original success value is returned unchanged.

When to Use

This is particularly useful when you want to standardize error handling or provide a consistent failure value for specific operations. It simplifies error management by ensuring that all failures are replaced with a controlled alternative.

Example

import { Effect } from "effect"

const validate = (age: number): Effect.Effect<number, string> => {
  if (age < 0) {
    return Effect.fail("NegativeAgeError")
  } else if (age < 18) {
    return Effect.fail("IllegalAgeError")
  } else {
    return Effect.succeed(age)
  }
}

const program = Effect.orElseFail(validate(-1), () => "invalid age")

console.log(Effect.runSyncExit(program))
// Output:
// {
//   _id: 'Exit',
//   _tag: 'Failure',
//   cause: { _id: 'Cause', _tag: 'Fail', failure: 'invalid age' }
// }

See

• mapError if you need to access the error to transform it.

Signature

declare const orElseFail: { <E2>(evaluate: LazyArg<E2>): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E2, R>; <A, E, R, E2>(self: Effect<A, E, R>, evaluate: LazyArg<E2>): Effect<A, E2, R>; }

Source

Since v2.0.0