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variable / @typed/fx

Fx.causes

Emits the source’s terminal failure cause and discards every successful value.

Package version
2.0.0-beta.7
Category
Errors and recovery
Since
1.0.0
Member of
Fx

Follow one execution

Emits the source’s terminal failure cause and discards every successful value.

Fx timelinecauses emits only the terminal Cause as a valuecauses
Operatorcauses
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 source is subscribed once. Success values are dropped in arrival order; a terminal cause is emitted once and the returned Fx completes without a typed error. Defects and interruption are retained inside the emitted cause. No resource is acquired beyond the source subscription.

Source implementation · Learn the surrounding model

Compare all Fx timelines →

Import

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

Access Fx.causes 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 causes: <A, E, R>(fx: Fx<A, E, R>) => Fx<Cause.Cause<E>, never, R>;

Why

Failure telemetry and supervision often need the complete Effect Cause without treating that cause as another failure. Materializing only the failure side makes those pipelines ordinary, infallible Fx values.

Ownership and lifetime

The source is subscribed once. Success values are dropped in arrival order; a terminal cause is emitted once and the returned Fx completes without a typed error. Defects and interruption are retained inside the emitted cause. No resource is acquired beyond the source subscription.

Examples

import { Cause } from "effect"
import { causes } from "@typed/fx/Fx"
import { failCause } from "@typed/fx/Fx"

const failures = causes(failCause(Cause.fail("offline")))

Other public imports

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

Source