# Fx.periodic

Creates an Fx that emits a `void` value periodically.

## Signatures

```ts
export declare const periodic: (period: Duration.Input) => Fx<void>;
```

## Why

Common interval work can use Effect's
[Schedule](https://effect.website/docs/v4/api/effect/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

```ts
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 }
})
```