Question

I essentially have a Future<List<T>> that is fetched in batches from the server. For some clients I’d like to provide incremental results while it loads in addition to the whole collection when future is fulfilled.

Is there a common Future extension defined somewhere for this? What are typical patterns/combinators exist for such futures?

I assume that given IncrementalListFuture<T> I can easily define map operation. What else comes to your mind?

Answer 1

To answer my own question: there has been lots of development in this area recently. Among most used are: Play iteratees (http://www.playframework.org/documentation/2.0/Iteratees) and Rx for .NET (http://msdn.microsoft.com/en-us/data/gg577609.aspx)

Instead of Future they define something like:

interface Observable<T> {
    Disposable subscribe(Observer<T> observer);
}

interface Observer<T> {
   void onCompleted();
   void onError(Exception error);
   void onNext(T value);
}

and lots of combinators.