I have just completed to develop the 7th topic in my on going course for learning F#. It covers the usage of generics and among other sub topics it explains how to define a generic class and how to define a generic function. If you are already familiar with generics you will find this topic easy to learn. If you are already familiar with functional programming languages this topic will be even simpler. You can find both the slides and the video clip available for free personal usage at www.abelski.com. You can find below few samples for the video clips I have just created for this topic.
The Visitor Design Pattern
The visitor design pattern allows us to add operations to objects that already exist without modifying their classes and without extending them.