Fx.onExit · API reference

Follow one execution

Pass the actual Exit to cleanup after the run; this lane depicts a successful Exit.

Fx timelineonExit(recordExit)onExit

Source

OperatoronExit(recordExit)

Lifecycle

Values

Read this diagram

Follow each lane from left to right. Events stacked vertically share a tick; the green cursor marks the current time across every lane.

A value
The text inside the pill is the emitted value.
Work starts
The raised chevron starts an inner run (^ in the source).
The run returns
The vertical bar ends this lane’s run.
A cause is delivered
The exclamation mark belongs to this lane.
Work is interrupted
The cross marks cancellation of this run.
Current time
The line and diamond move together across all lanes.
Happening now
A highlighted event is at the current tick.
Still ahead
Muted, dashed values have not happened yet.
Time continues
The lane’s arrow is not a return marker. An empty stretch can be quiet work that is still running.

Illustrated ticks start at 0. At 1×, one illustrated tick takes one second; captions specify real durations when timing matters. A cause or interruption belongs to its lane, and other work may continue. Scroll horizontally to inspect the rest of a long timeline.

The finalizer runs once after successful completion, a reported source cause, or interruption of the running fiber. The success Exit carries void because an Fx may emit many values and has no single terminal success value. A finalizer failure after normal completion is reported in the returned error channel. After a source failure or interruption it is suppressed so the already-observed termination remains authoritative. Finalizer services live for the subscription only.

Source implementation · Learn the surrounding model

Compare all Fx timelines →

Import

import { Fx } from "@typed/fx";

Access Fx.onExit through the imported Fx export. Its declaration below describes the member.

This public exposure is a re-export. Its import path is supported; declaration documentation is shared with the other public exposures below.

Signatures

export declare const onExit: {
    <A, E, XE = never, XR = never>(f: (exit: Exit.Exit<void, E>) => void | Effect.Effect<void, XE, XR>): <R>(self: Fx<A, E, R>) => Fx<A, E | XE, R | XR>;
    <A, E, R, XE = never, XR = never>(self: Fx<A, E, R>, f: (exit: Exit.Exit<void, E>) => void | Effect.Effect<void, XE, XR>): Fx<A, E | XE, R | XR>;
};

Why

Teardown and audit work sometimes depends on how the complete subscription ended. An Exit preserves that distinction without materializing it as a stream value.

Ownership and lifetime

Examples

import { Effect, Exit } from "effect"
import { onExit } from "@typed/fx/Fx"
import { succeed } from "@typed/fx/Fx"

const audited = onExit(succeed("ready"), (exit) =>
  Effect.log(Exit.isSuccess(exit) ? "complete" : "failed")
)

Other public imports

These import paths expose the same declaration. Each page retains its own public name and signature.

onExit from @typed/fx/Fx