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variable / @typed/fx

Fx.loopCauseEffect

Effectfully loops over the failure causes of an Fx with an accumulator.

Package version
2.0.0-beta.7
Category
Stateful transforms
Since
1.0.0
Member of
Fx

Follow one execution

Effectfully loops over the failure causes of an Fx with an accumulator.

Fx timelineloopCauseEffect forwards its transformed terminal cause when its Effect resolvesloopCauseEffect
OperatorloopCauseEffect(0, oneTurnPrefix)
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.

One mutable seed belongs to each run. Required services remain in the result; callback failure is delivered to the Sink, and interruption follows each producer delivery without adding a lock.

Source implementation · Learn the surrounding model

Compare all Fx timelines →

Import

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

Access Fx.loopCauseEffect 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 loopCauseEffect: {
    <B, A, E, R2, C>(seed: B, f: (acc: B, a: Cause.Cause<A>) => Effect.Effect<readonly [
        Cause.Cause<C>,
        B
    ], R2>): <R>(self: Fx<A, E, R>) => Fx<A, C | E, R | R2>;
    <A, E, R, B, R2, C>(self: Fx<A, E, R>, seed: B, f: (acc: B, a: Cause.Cause<E>) => Effect.Effect<readonly [
        Cause.Cause<C>,
        B
    ], E, R2>): Fx<A, C, R | R2>;
};

Why

loopCauseEffect allows cause transformation to consult services or perform Effects while retaining state between failures. It does not serialize concurrent failure deliveries, so overlapping callbacks can read the same seed and commit in completion order.

Ownership and lifetime

One mutable seed belongs to each run. Required services remain in the result; callback failure is delivered to the Sink, and interruption follows each producer delivery without adding a lock.

Examples

import { Effect } from "effect"
import { Fx } from "@typed/fx"

const observed = Fx.fail("offline").pipe(Fx.loopCauseEffect(0, (n, cause) => Effect.succeed([cause, n + 1])))

Other public imports

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

Source