# isFailure

Tests whether an AsyncData value contains an Effect Cause.

## Signatures

```ts
export declare const isFailure: <A, E>(asyncData: AsyncData<A, E>) => asyncData is Failure<E>;
```

## Why

The refinement exposes complete failure information without treating optimistic history as a current failure.

## Ownership and lifetime

This pure predicate acquires no resources and does not retain its argument.

## Examples

```ts
import { failure, isFailure } from "@typed/async-data"
import { Cause } from "effect"
isFailure(failure(Cause.fail("offline")))
```