Search documentation

Search by topic, API name, or import path.

GitHub ↗

variable / @typed/fx

Fx.collectUpTo

Collects the first n values emitted by an Fx into an array.

Package version
2.0.0-beta.13
Category
Collecting values
Since
1.0.0
Member of
Fx

Follow one execution

Stop after two values and return the retained prefix; cancel remaining producer work.

Fx timelinecollectUpTo(source, 2)collectUpTo
OperatorcollectUpTo(source, 2)
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.

Each Effect run owns a fresh array and source subscription. At most upTo values are retained in producer order; reaching the bound requests early exit and cleans up upstream. If the source completes first, the shorter array is returned. Source failures before completion remain typed.

Source implementation · Learn the surrounding model

Compare all Fx timelines →

Import

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

Access Fx.collectUpTo 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 collectUpTo: {
    (upTo: number): <A, E, R>(fx: Fx<A, E, R>) => Effect.Effect<ReadonlyArray<A>, E, R>;
    <A, E, R>(fx: Fx<A, E, R>, upTo: number): Effect.Effect<ReadonlyArray<A>, E, R>;
};

Why

collectUpTo creates a bounded pull result from a push source and stops upstream as soon as the requested cardinality has arrived.

Ownership and lifetime

Each Effect run owns a fresh array and source subscription. At most upTo values are retained in producer order; reaching the bound requests early exit and cleans up upstream. If the source completes first, the shorter array is returned. Source failures before completion remain typed.

Examples

import { collectUpTo, fromIterable } from "@typed/fx/Fx"

const firstTwo = collectUpTo(fromIterable([1, 2, 3]), 2)

Other public imports

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

Source