# causes

Emits the source's terminal failure cause and discards every successful value.

## Signatures

```ts
export declare const causes: <A, E, R>(fx: Fx<A, E, R>) => Fx<Cause.Cause<E>, never, R>;
```

## Why

Failure telemetry and supervision often need the complete Effect `Cause`
without treating that cause as another failure. Materializing only the
failure side makes those pipelines ordinary, infallible Fx values.

## Ownership and lifetime

The source is subscribed once. Success values are dropped in arrival order;
a terminal cause is emitted once and the returned Fx completes without a
typed error. Defects and interruption are retained inside the emitted cause.
No resource is acquired beyond the source subscription.

## Examples

```ts
import { Cause } from "effect"
import { causes } from "@typed/fx/Fx"
import { failCause } from "@typed/fx/Fx"

const failures = causes(failCause(Cause.fail("offline")))
```