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Fx.raceAll

Races many streams: the first to emit wins and the rest are interrupted.

Package version
2.0.0-beta.7
Category
Concurrent work
Since
1.0.0
Member of
Fx

Follow one execution

Races many streams: the first to emit wins and the rest are interrupted.

Fx timelineraceAll keeps fast and cancels the other candidatesraceAll
OperatorraceAll(slow, fast, mid)
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.

Before selection, the first non-interruption failure is retained and reported only if every input ends without emitting. After selection, winner failures are forwarded. All environments are required. Losers are interrupted and the observing fiber owns cleanup for every child.

Source implementation · Learn the surrounding model

Compare all Fx timelines →

Import

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

Access Fx.raceAll 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 raceAll: <FX extends ReadonlyArray<Fx<any, any, any>>>(...fxs: FX) => Fx<Fx.Success<FX[number]>, Fx.Error<FX[number]>, Fx.Services<FX[number]>>;

Why

raceAll extends {@link race} to a runtime-sized set while preserving the first-value selection rule.

Selection, ordering, and cardinality

All inputs start concurrently. The first emitted value selects one input and only that input’s values are forwarded afterward. Zero inputs produce the empty Fx; one input is returned unchanged. No result buffer is retained.

Ownership and lifetime

Before selection, the first non-interruption failure is retained and reported only if every input ends without emitting. After selection, winner failures are forwarded. All environments are required. Losers are interrupted and the observing fiber owns cleanup for every child.

Examples

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

const response = Fx.raceAll(
  Fx.at("cache", "30 millis"),
  Fx.at("primary", "5 millis"),
  Fx.at("replica", "20 millis")
)
Effect.runPromise(Fx.collectAll(response)).then(console.log)
// ["primary"]

Other public imports

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

Source