# operator: use

{% hint style="info" %}
Since version 4.0 `use` operator is deprecated. You can easily compose middlewares directly to the Observable chain.
{% endhint %}

### **Importing**

```typescript
import { use } from '@marblejs/core';
```

### **Type declaration**

```typescript
use :: <I, O>(MiddlewareLike<I, O>, <?>EffectContext) -> Observable<I>
```

### **Parameters**

| *parameter*  | definition                    |
| ------------ | ----------------------------- |
| *middleware* | `MiddlewareLike`              |
| ctx          | *\<optional>* `EffectContext` |

### **Returns**

`Observable<I>`

### Example

```typescript
import { use } from '@marblejs/core';
import { r } from '@marblejs/http';

const foo$ = r.pipe(
  r.matchPath('/'),
  r.matchType('GET'),
  r.useEffet(req$ => req$.pipe(
    // ...
    use(authorize$),
    // ...
  )));
```