# optimistic

Adds an optimistic value above an existing AsyncData history.

## Signatures

```ts
export declare const optimistic: <A, E>(previous: AsyncData<A, E>, value: A) => Optimistic<A, E>;
```

## Why

Keeping `previous` makes rollback and reconciliation explicit rather than mutating or discarding earlier state.

## Ownership and lifetime

This pure function acquires no resources; the wrapper retains both supplied values.

## Examples

```ts
import { optimistic, success } from "@typed/async-data"
const state = optimistic(success("saved"), "saving")
```