Model time, repetition, and rate

Timing operators declare when work or delivery should happen. A postponed search, a periodic poll, and a silent connection each need a different rule; compose that rule with the producer instead of managing timer handles alongside it. Start with Transforming Fx, then apply a clock only where the feature can name its outcome.

Separate postponed delivery from omitted input

import { Fx } from "@typed/fx"

const input = Fx.fromIterable(["t", "ty", "typed"])

const delayed = input.pipe(Fx.delay("100 millis"))
const settled = input.pipe(Fx.debounce("250 millis"))
const preview = input.pipe(Fx.throttle("100 millis"))

delay postpones every value. debounce keeps only the value that remains current through its quiet period. throttle limits a window according to its configured leading/trailing policy. Put normalization and admission before debounce when short input should not reset the clock.

Test the search rule using the clock it actually runs on

import { Effect, Fiber } from "effect"
import { expect, it } from "@effect/vitest"
import * as TestClock from "effect/testing/TestClock"
import { Fx } from "@typed/fx"

const settledQuery = Effect.fn(function* () {
  const search = Fx.mergeAll(Fx.at("ty", "0 millis"), Fx.at("typed", "50 millis")).pipe(
    Fx.debounce("200 millis"),
  )

  const fiber = yield* Effect.forkScoped(Fx.collectAll(search))

  yield* TestClock.adjust("250 millis")

  expect(yield* Fiber.join(fiber)).toEqual(["typed"])
})

it.effect("keeps only the settled query", () =>
  settledQuery().pipe(Effect.provide(TestClock.layer()), Effect.scoped),
)

Advance the same Effect clock that owns the source.

Poll by completion or tick on a schedule

import { Schedule } from "effect"
import { Fx } from "@typed/fx"

const poll = Fx.fromSchedule(Schedule.recurs(2))
const repeated = Fx.succeed("checked").pipe(Fx.repeat(Schedule.recurs(2)))
const heartbeat = Fx.periodic("1 second")

repeat starts a fresh run only after the preceding one completes. periodic emits clock ticks; use a higher-order mapper only after deciding whether an unfinished request may overlap its next tick. Failure is not repetition: recovery owns retry policy.

Decide whether silence ends the feed or selects a fallback

import { Fx } from "@typed/fx"

const heartbeat = Fx.periodic("1 second")

const connectionEnded = heartbeat.pipe(Fx.timeout("2 seconds"))
const availability = heartbeat.pipe(Fx.timeoutTo("2 seconds", Fx.succeed("offline")))

timeout completes normally after the chosen silence. timeoutTo instead interrupts the source and begins a fallback. Neither proves a server disconnected; each models the application threshold.

For clock policies applied to browser events, dynamic producers covers event registration and cleanup.

Continue with errors and recovery when a timed request fails or retries; services and lifetime attaches these clocks to a feature owner.