# loopCauseEffect

Threads state through an effectful failure transformation.

## Signatures

```ts
export declare const loopCauseEffect: {
    <A, E, R2, B, C>(seed: B, f: (acc: B, a: Cause.Cause<E>) => Effect.Effect<readonly [
        Cause.Cause<C>,
        B
    ], E, R2>): <R>(sink: Sink<A, E | C, R>) => Sink<A, E, R | R2>;
    <A, E, R, B, C, R2>(sink: Sink<A, E | C, R>, seed: B, f: (acc: B, a: Cause.Cause<E>) => Effect.Effect<readonly [
        Cause.Cause<C>,
        B
    ], E, R2>): Sink<A, E, R | R2>;
};
```

## Why

Failure handling can consult services and retain state while preserving the original Cause when
the handler itself fails.

## Ownership and lifetime

Callback invocation constructs a transition Effect from the seed visible at that moment. The
adapter does not serialize those Effects: overlapping failures can read the same seed, and
successful transitions commit in completion order. A transition failure is combined with the
original cause and does not commit. Success values bypass the state machine. The sink instance
retains its seed across producer runs; construct a new one to reset it.

## Examples

```ts
import { Effect } from "effect"
import * as Sink from "@typed/fx/Sink"
const target = Sink.make(Effect.logError, Effect.log)
const sink = Sink.loopCauseEffect(target, 0, (count, cause) => Effect.succeed([cause, count + 1] as const))
```