# at

Creates an Fx that emits a single value after a specified delay.

## Signatures

```ts
export declare const at: {
    (delay: Duration.Input): <A>(value: A) => Fx<A>;
    <A>(value: A, delay: Duration.Input): Fx<A>;
};
```

## Why

`at` models a one-shot producer while keeping the delay inside Effect's
interruptible scheduling rather than an unmanaged timer callback.

## Ownership and lifetime

Construction starts no timer. Running the `Fx` sleeps, emits exactly once, and
completes after the sink handles the value. Interrupting the run cancels the sleep.

## Examples

```ts
import { Effect } from "effect"
import { at, first } from "@typed/fx/Fx"

const delayed = at("ready", "10 millis")
const program = Effect.map(first(delayed), (value) => value)
```