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variable / @typed/fx/Fx

loopCause

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

Follow one execution

Loops over the failure causes of an Fx with an accumulator.

Fx timelineloopCause rewrites a terminal cause after passing earlier values throughloopCause
OperatorloopCause(0, prefix)
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.

A fresh state begins for each run and is discarded afterward. The callback owns no resources and sees typed failures, defects, and interruption represented by Cause.

Source implementation · Learn the surrounding model

Compare all Fx timelines →

Import

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

Signatures

export declare const loopCause: {
    <B, A, C>(seed: B, f: (acc: B, a: Cause.Cause<A>) => readonly [
        Cause.Cause<C>,
        B
    ]): <E, R>(self: Fx<A, E, R>) => Fx<A, C, R>;
    <A, E, R, B, C>(self: Fx<A, E, R>, seed: B, f: (acc: B, a: Cause.Cause<E>) => readonly [
        Cause.Cause<C>,
        B
    ]): Fx<A, C, R>;
};

Why

loopCause is the stateful counterpart of error mapping over full Effect causes. Successful values pass unchanged; each cause is synchronously transformed and advances the error state.

Ownership and lifetime

A fresh state begins for each run and is discarded afterward. The callback owns no resources and sees typed failures, defects, and interruption represented by Cause.

Examples

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

const numbered = Fx.fail("offline").pipe(Fx.loopCause(0, (n, cause) => [Cause.map(cause, (e) => `${n}:${e}`), n + 1]))

Other public imports

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

Source