# RefResult.map

Map the success value of a RefResult.

## Signatures

```ts
export declare const map: {
    <A, B>(f: (a: A) => B): <ResultE, Err, R>(ref: RefResult<A, ResultE, Err, R>) => RefSubject.Computed<Result.Result<B, ResultE>, Err, R>;
    <A, ResultE, Err, R, B>(ref: RefResult<A, ResultE, Err, R>, f: (a: A) => B): RefSubject.Computed<Result.Result<B, ResultE>, Err, R>;
};
```

## Why

Projects result state with map for both current reads and future pushes, avoiding a second
mutable cache of the derived value.

## Ownership and lifetime

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