# Sink.loopCause

Threads pure state through failure causes and forwards one transformed cause per failure.

## Signatures

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

## Why

Stateful error translation can retain retry or protocol context while preserving full Cause
information.

## Ownership and lifetime

Each adapted sink owns its seed. Failure callbacks update it synchronously in invocation order;
successes pass through unchanged. Reusing the sink continues from its retained seed; create a new
sink to reset. No resources are acquired.

## Examples

```ts
import { Cause, Effect } from "effect"
import * as Sink from "@typed/fx/Sink"
const target: Sink.Sink<number, string> = Sink.make(Effect.logError, Effect.log)
const counted = Sink.loopCause(target, 0, (n, cause: Cause.Cause<string>) => [cause, n + 1])
```