Add stream interface for observable lists

[tobiasdiez]

Idea: Have an interface that works similar to List.stream() but takes updates into account.

Similar implementation: https://github.com/griffon/griffon/blob/development/subprojects/griffon-javafx/src/main/java/griffon/javafx/collections/ObservableStream.java

[piegamesde]

Is this something that requires some planning and careful implementation according to an interface? Or can we simply go ahead and add convenience methods to EasyObservableList inspired by this? (I'd really like EasyObservableList#map)

[tobiasdiez]

New convenient helper methods are always happily seen!

A proper stream-like interface is more work as one has to worry about chaining different operations. For the best performance, you don't want to create an intermediate list, and then listen to change events to this list; but you would like to listen to events of the original source and then transverse the stream-chain to only update the resulting list.

[piegamesde]

Ah, I see. So the difficulty does not lie in the API design, but in an efficient implementation. Thus, the methods can already be added with a naive implementation, and optimized afterwards?

[tobiasdiez]

Yes, exactly!