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Fx.zip

Zips two Fx streams in strict lockstep: emits a pair [a, b] only when both streams have produced their next value. Emits the i-th pair when both have produced at least i values.

Completion: The zipped stream completes when the first of the two streams completes (no further pairs are emitted). The other stream is interrupted.

Errors: The first failure from either stream fails the zipped stream.

Package version
2.0.0-beta.13
Category
Combining sources
Since
1.0.0
Member of
Fx

Follow one execution

Wait for a fresh value from each side for each pair.

Fx timelinezip(left, right)zip
Operatorzip(left, right)
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.

Both child runs and queues belong to the consumer. The first completion, any failure, or interruption stops both fibers and discards unmatched queued values.

Source implementation · Learn the surrounding model

Compare all Fx timelines →

Import

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

Access Fx.zip 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 zip: {
    <A2, E2, R2>(that: Fx<A2, E2, R2>): <A, E, R>(self: Fx<A, E, R>) => Fx<readonly [
        A,
        A2
    ], E | E2, R | R2>;
    <A, E, R, A2, E2, R2>(self: Fx<A, E, R>, that: Fx<A2, E2, R2>): Fx<readonly [
        A,
        A2
    ], E | E2, R | R2>;
};

Why

zip preserves one-to-one positional correspondence between two producers. Values wait in unbounded queues until their counterpart arrives, and pairs emit in each source’s order.

Ownership and lifetime

Both child runs and queues belong to the consumer. The first completion, any failure, or interruption stops both fibers and discards unmatched queued values.

Examples

import { Fx } from "@typed/fx"
const pairs = Fx.zip(Fx.fromIterable([1, 2]), Fx.fromIterable(["a", "b"]))

Other public imports

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

Source