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Fx.withSpan

Traces the whole subscription and each success or failure delivery.

Package version
2.0.0-beta.7
Category
Observing failures
Since
1.0.0
Member of
Fx

Follow one execution

Traces the whole subscription and each success or failure delivery.

Fx timelinewithSpan adds trace lifetimes around an otherwise unchanged subscriptionwithSpan
OperatorwithSpan("market monitor")
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.

Every run creates an Fx(name) span covering the source subscription. Each onSuccess and onFailure callback executes in its own child span. Span lifetime follows the Effects exactly; interruption closes active spans. Options are forwarded to all three span kinds, and no service requirement or failure is added beyond the configured Effect tracer.

Source implementation · Learn the surrounding model

Compare all Fx timelines →

Import

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

Access Fx.withSpan 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 withSpan: {
    (name: string, options?: SpanOptionsNoTrace): <A, E, R>(fx: Fx<A, E, R>) => Fx<A, E, R>;
    <A, E, R>(fx: Fx<A, E, R>, name: string, options?: SpanOptionsNoTrace): Fx<A, E, R>;
};

Why

A single Effect span around subscription setup cannot show time spent in downstream sink callbacks. Nested delivery spans make the push boundary visible while keeping the source’s values and types unchanged.

Ownership and lifetime

Every run creates an Fx(name) span covering the source subscription. Each onSuccess and onFailure callback executes in its own child span. Span lifetime follows the Effects exactly; interruption closes active spans. Options are forwarded to all three span kinds, and no service requirement or failure is added beyond the configured Effect tracer.

Examples

import { withSpan } from "@typed/fx/Fx"
import { succeed } from "@typed/fx/Fx"

const traced = withSpan(succeed("ready"), "load-settings", {
  attributes: { component: "settings" }
})

Other public imports

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

Source