# RefSubject.getOrElse

Returns a `Computed` that yields the value inside the `Option`, or the fallback when `None`.
Works with `Computed<Option<A>>` (e.g. from `fromOption` / `fromNullable`) and with `Filtered<A>`.

## Signatures

```ts
export declare const getOrElse: {
    <A>(fallback: () => A): <E, R>(ref: Computed<Option.Option<A>, E, R> | Filtered<A, E, R>) => Computed<A, E, R>;
    <A, E, R>(ref: Computed<Option.Option<A>, E, R> | Filtered<A, E, R>, fallback: () => A): Computed<A, E, R>;
};
```

## Why

Returns a `Computed` that yields the value inside the `Option`, or the fallback when `None`.
Works with `Computed<Option<A>>` (e.g. from `fromOption` / `fromNullable`) and with
`Filtered<A>`. Current reads and pushed versions use the same derivation, preventing snapshot
and subscription behavior from diverging.

## Ownership and lifetime

The returned Computed never fails for absence: `None` or an absent Filtered value invokes
`fallback`. It preserves only the input's declared `E` and `R`; the pure fallback adds no failure,
service, subscription, or retained value.

## Examples

```ts
import { Effect, Option } from "effect"
import * as RefSubject from "@typed/fx/RefSubject"

const program = Effect.gen(function* () {
  const ref = yield* RefSubject.fromOption(Option.some(42))
  const withDefault = RefSubject.getOrElse(ref, () => 0)
  expect(yield* withDefault).toBe(42)

  const empty = yield* RefSubject.fromNullable(null)
  const fallback = RefSubject.getOrElse(empty, () => 99)
  expect(yield* fallback).toBe(99)
})
```