# during

Forwards `events` only between a start signal and that signal's first stop event.

## Signatures

```ts
export declare function during<A, E, R, Start extends Fx.Any, E2, R2>(events: Fx<A, E, R>, signals: Fx<Start, E2, R2>): Fx<A, E | E2 | Fx.Error<Start>, R | R2 | Fx.Services<Start> | Scope.Scope>;
```

## Why

Push lifetimes are often controlled by other push lifetimes: a pointer move
matters between pointer-down and pointer-up, for example. `during` models
that gate without converting either side into polling state.

## Ownership and lifetime

`events` and the outer `signals` Fx start concurrently in one child Scope.
Only the first outer value is used; that value must itself be an Fx, whose
first value closes the gate. Event values before the start signal and after
the stop signal are discarded. Completion of `events` completes the result.
A failure from events, signals, or the selected stop Fx terminates everything;
closing or interrupting the returned Fx interrupts all remaining fibers and
closes the private Scope.

## Examples

```ts
import { during } from "@typed/fx/Fx"
import { delay } from "@typed/fx/Fx"
import { periodic, succeed } from "@typed/fx/Fx"

const pointerMoves = periodic("16 millis")
const pointerDown = succeed(delay(succeed(undefined), "1 second"))
const activeMoves = during(pointerMoves, pointerDown)
```