# isLessThan

Check if the current state of a RefDuration is less than a Duration.

## Signatures

```ts
export declare const isLessThan: {
    (that: Duration.Duration): <E, R>(ref: RefDuration<E, R>) => RefSubject.Computed<boolean, E, R>;
    <E, R>(ref: RefDuration<E, R>, that: Duration.Duration): RefSubject.Computed<boolean, E, R>;
};
```

## Why

Check if the current state of a RefDuration is less than a Duration. The operation remains
attached to the RefSubject's versioned state boundary.

## Ownership and lifetime

The is less than view retains no independent state. An Effect read samples the source once; Fx
observation follows later pushes and its observing Scope owns subscription cleanup.