effect-io-ai

Package: effect
Module: Effect

Effect.runFork

Runs an effect in the background, returning a fiber that can be observed or interrupted.

Unless you specifically need a Promise or synchronous operation, runFork is a good default choice.

Details

This function is the foundational way to execute an effect in the background. It creates a “fiber,” a lightweight, cooperative thread of execution that can be observed (to access its result), interrupted, or joined. Fibers are useful for concurrent programming and allow effects to run independently of the main program flow.

Once the effect is running in a fiber, you can monitor its progress, cancel it if necessary, or retrieve its result when it completes. If the effect fails, the fiber will propagate the failure, which you can observe and handle.

When to Use

Use this function when you need to run an effect in the background, especially if the effect is long-running or performs periodic tasks. It’s suitable for tasks that need to run independently but might still need observation or management, like logging, monitoring, or scheduled tasks.

This function is ideal if you don’t need the result immediately or if the effect is part of a larger concurrent workflow.

Example (Running an Effect in the Background)

import { Effect, Console, Schedule, Fiber } from "effect"

//      ┌─── Effect<number, never, never>
//      ▼
const program = Effect.repeat(
  Console.log("running..."),
  Schedule.spaced("200 millis")
)

//      ┌─── RuntimeFiber<number, never>
//      ▼
const fiber = Effect.runFork(program)

setTimeout(() => {
  Effect.runFork(Fiber.interrupt(fiber))
}, 500)

Signature

declare const runFork: <A, E>(effect: Effect<A, E>, options?: Runtime.RunForkOptions) => Fiber.RuntimeFiber<A, E>

Source

Since v2.0.0