# RefIterable.head

Get the first element of a RefIterable as a Filtered.

## Signatures

```ts
export declare const head: <A, E, R>(ref: RefIterable<A, E, R>) => RefSubject.Filtered<A, E, R>;
```

## Why

Models the possibly absent result of head as Filtered state, so absence stays explicit while
later source versions can make a value available.

## Ownership and lifetime

The head view retains no independent value. Its Effect read fails with NoSuchElement
while absent; the observing Scope owns and finalizes its Fx subscription.