An important article for dot net developers. What are Iterator Patterns? To know, read this article and see an example of Ienumerable, Ienumerator and foreach.
"Rx is a superset of the standard LINQ sequence operators that exposes asynchronous and event-based computations as push-based, observable collections via the new .NET 4.0 interfaces IObservable and IObserver. These are the mathematical dual of the familiar IEnumerable and IEnumerator interfaces for pull-based, enumerable collections in the .NET framework. "