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variable / @typed/fx/Fx

zipLatestWith

Zips two Fx streams by latest values and combines each pair with a function. Waits for both to emit at least once, then emits f(left, right) whenever either stream emits.

Completion: Completes when both streams have completed. Errors: The first failure from either stream fails the result.

Package version
2.0.0-beta.7
Category
Combining sources
Since
1.0.0

Follow one execution

Apply the combining function to each latest-value pair.

Fx timelinezipLatestWith(query, filter, search)zipLatestWith
OperatorzipLatestWith(query, filter, search)
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 concurrent sources and their retained latest values are owned by the consumer. The combiner is pure; failure, services, completion, and interruption come from the inputs.

Source implementation · Learn the surrounding model

Compare all Fx timelines →

Import

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

Signatures

export declare const zipLatestWith: {
    <AL, AR, ER, RR, B>(that: Fx<AR, ER, RR>, f: (left: AL, right: AR) => B): <EL, RL>(self: Fx<AL, EL, RL>) => Fx<B, EL | ER, RL | RR>;
    <AL, EL, RL, AR, ER, RR, B>(self: Fx<AL, EL, RL>, that: Fx<AR, ER, RR>, f: (left: AL, right: AR) => B): Fx<B, EL | ER, RL | RR>;
};

Why

zipLatestWith projects latest-value pairs whenever either initialized source updates. The synchronous callback changes payloads without changing zipLatest cardinality.

Ownership and lifetime

Both concurrent sources and their retained latest values are owned by the consumer. The combiner is pure; failure, services, completion, and interruption come from the inputs.

Examples

import { Fx } from "@typed/fx"
const label = Fx.zipLatestWith(Fx.succeed(1), Fx.succeed("item"), (n, kind) => `${kind}-${n}`)

Other public imports

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

Source