reactor-async

name	reactor-async
description	Async data in Reactor — `UseResource` (single fetch), `UseMutation` (writes + optimistic updates), `UseInfiniteResource` (cursor pagination), and `Pending` (bubble-up fallback). Use when fetching, caching, paginating, or mutating server data.

Async Resources in Reactor

Reactor replaces the UseState + UseEffect + manual-cancellation dance with three hooks. Reads return AsyncValue<T>, writes return a Mutation handle. The hook owns the cancellation token, dedups across siblings, caches results in a shared QueryCache, and drops late results on unmount.

Available on any Component subclass directly; on RenderContext as extension methods for function components (Memo(ctx => ...) or RenderEachTime(ctx => ...)).

1. UseResource — single fetch

AsyncValue<T> UseResource<T>(
    Func<CancellationToken, Task<T>> fetcher,
    object[] deps,
    ResourceOptions? options = null);

AsyncValue<T> is a sealed 4-state record: Loading, Data(T Value), Error(Exception), Reloading(T Previous) (stale-while-revalidate). Pattern-match with a switch:

class UserCard : Component
{
      Element ()
    {
         user = UseResource(
            ct => Api.GetUserAsync(userId, ct),
            deps:  [] { userId });

         user 
        {
            AsyncValue<User>.Loading   => TextBlock(),
            AsyncValue<User>.Data d    => TextBlock(d.Value.Name).Bold(),
            AsyncValue<User>.Reloading r => TextBlock(r.Previous.Name).Opacity(),
            AsyncValue<User>.Error e   => TextBlock(),
            _ => Empty()
        };
    }
}