effect-io-ai

Package: effect
Module: Effect

Effect.timeoutOrElse

Applies a timeout to an effect, with a fallback effect executed if the timeout is reached.

When to use

Use when a timeout of an Effect should switch to a fallback effect.

Details

The fallback effect is created lazily by orElse and may introduce its own success, failure, and requirement types.

Gotchas

If the timeout wins, the source effect is interrupted before the fallback is run.

Example (Falling back on timeout)

import { Console, Effect } from "effect"

const slowQuery = Effect.gen(function*() {
  yield* Console.log("Starting database query...")
  yield* Effect.sleep("5 seconds")
  return "Database result"
})

// Use cached data as fallback when timeout is reached
const program = Effect.timeoutOrElse(slowQuery, {
  duration: "2 seconds",
  orElse: () =>
    Effect.gen(function*() {
      yield* Console.log("Query timed out, using cached data")
      return "Cached result"
    })
})

Effect.runPromise(program).then(console.log)
// Output:
// Starting database query...
// Query timed out, using cached data
// Cached result

See

• timeout for failing with a TimeoutException.
• timeoutOption for returning Option.none on timeout.

Signature

declare const timeoutOrElse: { <A2, E2, R2>(options: { readonly duration: Duration.Input; readonly orElse: LazyArg<Effect<A2, E2, R2>>; }): <A, E, R>(self: Effect<A, E, R>) => Effect<A | A2, E | E2, R | R2>; <A, E, R, A2, E2, R2>(self: Effect<A, E, R>, options: { readonly duration: Duration.Input; readonly orElse: LazyArg<Effect<A2, E2, R2>>; }): Effect<A | A2, E | E2, R | R2>; }

Source

Since v4.0.0