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variable / @typed/fx

Fx.periodic

Creates an Fx that emits a void value periodically.

Package version
2.0.0-beta.7
Category
Time and rate
Since
1.0.0
Member of
Fx

Follow one execution

One-second slots: the first void tick follows the first period. Consumer interruption cancels future ticks.

Fx timelineperiodic("2 seconds")periodic
Operatorperiodic("2 seconds")
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.

Construction starts no clock. A run waits period before the first emission and again between every subsequent emission. The run fiber owns the schedule; no ticks continue after interruption.

Source implementation · Learn the surrounding model

Compare all Fx timelines →

Import

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

Access Fx.periodic 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 periodic: (period: Duration.Input) => Fx<void>;

Why

Common interval work can use Effect’s Schedule clock and interruption semantics rather than an unmanaged platform timer.

Ownership and lifetime

Construction starts no clock. A run waits period before the first emission and again between every subsequent emission. The run fiber owns the schedule; no ticks continue after interruption.

Examples

import { Effect, Fiber } from "effect"
import * as TestClock from "effect/testing/TestClock"
import { collectUpTo, periodic } from "@typed/fx/Fx"

const program = Effect.gen(function* () {
  const fiber = yield* Effect.forkChild(collectUpTo(periodic("1 second"), 1))
  yield* TestClock.adjust("999 millis")
  const beforeFirstPeriod = fiber.pollUnsafe()
  yield* TestClock.adjust("1 millis")
  const firstTick = yield* Fiber.join(fiber)
  return { beforeFirstPeriod, firstTick }
})

Other public imports

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

Source