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variable / @typed/fx/Fx

exhaustMapEffect

Maps each element of an Fx to an Effect, ignoring new elements until the current effect completes.

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

Follow one execution

Ignore b while a is running; accept c after a completes.

Fx timelineexhaustMapEffect(submit)exhaustMapEffect
OperatorexhaustMapEffect(submit)
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 Effect failures remain typed and callback services are added to the output requirements. The active Effect is owned by the returned Fx’s required Scope; completion waits for it and interruption runs its finalizers.

Source implementation · Learn the surrounding model

Compare all Fx timelines →

Import

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

Signatures

export declare const exhaustMapEffect: FlatMapEffectLike;

Why

This Effect-producing form of {@link exhaustMap } prevents overlapping command Effects while deliberately applying no queue or latest-value replay policy.

Admission and cardinality

The first value while idle starts one Effect and emits its one successful result. For values received while it runs, f is still evaluated to construct an Effect, but that Effect is not run or queued.

Ownership and lifetime

Source and callback Effect failures remain typed and callback services are added to the output requirements. The active Effect is owned by the returned Fx’s required Scope; completion waits for it and interruption runs its finalizers.

Examples

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

const accepted = Fx.exhaustMapEffect(Fx.fromIterable([1, 2]), (id) =>
  Effect.as(Effect.sleep("20 millis"), `saved:${id}`)
)

Effect.runPromise(Effect.scoped(Fx.collectAll(accepted))).then(console.log)
// ["saved:1"]: the second Effect is constructed but not admitted

Other public imports

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

Source