effect-io-ai

Package: effect
Module: Effect

Effect.retry

Retries typed failures from an effect according to a retry policy.

When to use

Use when you need to rerun an effect after transient typed failures, such as network issues or temporary resource unavailability.

Details

The policy can be a Schedule, a schedule builder, or a Retry.Options object using schedule, times, while, or until. If a retry eventually succeeds, the returned effect succeeds with that value. If the policy stops while the effect is still failing, the last failure is propagated.

Gotchas

The source effect is always evaluated once before any retry policy is applied. For example, Schedule.recurs(3) allows up to three retries after the initial attempt.

Defects and interruptions are not retried.

Example (Retrying with a schedule)

import { Data, Effect, Schedule } from "effect"

class AttemptError extends Data.TaggedError("AttemptError")<{ readonly attempt: number }> {}

let attempt = 0
const task = Effect.callback<string, AttemptError>((resume) => {
  attempt++
  if (attempt <= 2) {
    resume(Effect.fail(new AttemptError({ attempt })))
  } else {
    resume(Effect.succeed("Success!"))
  }
})

const policy = Schedule.addDelay(Schedule.recurs(5), () => Effect.succeed("100 millis"))
const program = Effect.retry(task, policy)

Effect.runPromise(program).then(console.log)
// Output: "Success!" (after 2 retries)

See

• retryOrElse for a version that allows you to run a fallback.
• repeat if your retry condition is based on successful outcomes rather than errors.

Signature

declare const retry: { <E, O extends Retry.Options<E>>(options: O): <A, R>(self: Effect<A, E, R>) => Retry.Return<R, E, A, O>; <B, E, Error, Env>(policy: Schedule<B, NoInfer<E>, Error, Env>): <A, R>(self: Effect<A, E, R>) => Effect<A, E | Error, R | Env>; <B, E, Error, Env>(builder: ($: <O, SE, R>(_: Schedule<O, NoInfer<E>, SE, R>) => Schedule<O, E, SE, R>) => Schedule<B, NoInfer<E>, Error, Env>): <A, R>(self: Effect<A, E, R>) => Effect<A, E | Error, R | Env>; <A, E, R, O extends Retry.Options<E>>(self: Effect<A, E, R>, options: O): Retry.Return<R, E, A, O>; <A, E, R, B, Error, Env>(self: Effect<A, E, R>, policy: Schedule<B, NoInfer<E>, Error, Env>): Effect<A, E | Error, R | Env>; <A, E, R, B, Error, Env>(self: Effect<A, E, R>, builder: ($: <O, SE, R>(_: Schedule<O, NoInfer<E>, SE, R>) => Schedule<O, E, SE, R>) => Schedule<B, NoInfer<E>, Error, Env>): Effect<A, E | Error, R | Env>; }

Source

Since v2.0.0