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variable / @typed/fx

Fx.flatMapEffect

Maps each element of an Fx to an Effect, and merges the results.

Package version
2.0.0-beta.13
Category
Concurrent work
Since
1.0.0
Member of
Fx

Follow one execution

Start both Effects; b resolves first. Completion waits for outstanding a.

Fx timelineflatMapEffect(load)flatMapEffect
OperatorflatMapEffect(load)
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.

Source and callback failures remain typed and callback services are unioned with source services. The required Scope owns all running Effects; source completion waits for them, and interruption runs every Effect finalizer.

Source implementation · Learn the surrounding model

Compare all Fx timelines →

Import

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

Access Fx.flatMapEffect 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 flatMapEffect: FlatMapEffectLike;

Why

This is the Effect-producing form of {@link flatMap }. It admits independent Effects directly without callers manually applying Fx.fromEffect.

Concurrency, ordering, and cardinality

Every source value starts one Effect with unbounded concurrency. Each successful Effect emits exactly one value. Results appear in completion order, not source order, and no output buffer restores ordering.

Ownership and lifetime

Source and callback failures remain typed and callback services are unioned with source services. The required Scope owns all running Effects; source completion waits for them, and interruption runs every Effect finalizer.

Examples

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

const loaded = Fx.flatMapEffect(Fx.fromIterable([
  { id: "slow", wait: "20 millis" as const },
  { id: "fast", wait: "1 millis" as const }
]), ({ id, wait }) => Effect.as(Effect.sleep(wait), id))

Effect.runPromise(Effect.scoped(Fx.collectAll(loaded))).then(console.log)
// ["fast", "slow"]

Other public imports

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

Source