# Fx.loopCauseEffect

Effectfully loops over the failure causes of an Fx with an accumulator.

## Signatures

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

## Why

`loopCauseEffect` allows cause transformation to consult services or perform Effects while
retaining state between failures. It does not serialize concurrent failure deliveries, so
overlapping callbacks can read the same seed and commit in completion order.

## Ownership and lifetime

One mutable seed belongs to each run. Required services remain in the result; callback failure is
delivered to the Sink, and interruption follows each producer delivery without adding a lock.

## Examples

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

const observed = Fx.fail("offline").pipe(Fx.loopCauseEffect(0, (n, cause) => Effect.succeed([cause, n + 1])))
```