effect-io-ai

Package: effect
Module: Effect

Effect.onExit

Guarantees that a cleanup function runs regardless of whether the effect succeeds, fails, or is interrupted.

Details

This function ensures that a provided cleanup function is executed after the effect completes, regardless of the outcome. The cleanup function is given the Exit value of the effect, which provides detailed information about the result:

• If the effect succeeds, the Exit contains the success value.
• If the effect fails, the Exit contains the error or failure cause.
• If the effect is interrupted, the Exit reflects the interruption.

The cleanup function is guaranteed to run uninterruptibly, ensuring reliable resource management even in complex or high-concurrency scenarios.

Example (Running a Cleanup Function with the Effect’s Result)

import { Console, Effect, Exit } from "effect"

// Define a cleanup effect that logs the result
const handler = Effect.onExit((exit) =>
  Console.log(`Cleanup completed: ${Exit.getOrElse(exit, String)}`)
)

// Define a successful effect
const success = Console.log("Task completed").pipe(
  Effect.as("some result"),
  handler
)

Effect.runFork(success)
// Output:
// Task completed
// Cleanup completed: some result

// Define a failing effect
const failure = Console.log("Task failed").pipe(
  Effect.andThen(Effect.fail("some error")),
  handler
)

Effect.runFork(failure)
// Output:
// Task failed
// Cleanup completed: Error: some error

// Define an interrupted effect
const interruption = Console.log("Task interrupted").pipe(
  Effect.andThen(Effect.interrupt),
  handler
)

Effect.runFork(interruption)
// Output:
// Task interrupted
// Cleanup completed: All fibers interrupted without errors.

Signature

declare const onExit: { <A, E, X, R2>(cleanup: (exit: Exit.Exit<A, E>) => Effect<X, never, R2>): <R>(self: Effect<A, E, R>) => Effect<A, E, R2 | R>; <A, E, R, X, R2>(self: Effect<A, E, R>, cleanup: (exit: Exit.Exit<A, E>) => Effect<X, never, R2>): Effect<A, E, R | R2>; }

Source

Since v2.0.0