We’ve kicked off C9 Lectures with a journey into the world of Functional Programming with functional language purist and high priest of the lambda calculus, Dr. Erik Meijer (you can thank Erik for many of the functional constructs that have shown up in languages like C# and VB.NET. When you use LINQ, thank Erik in addition to Anders).  We will release a new chapter in this series every Thursday. In Chapter 6, Dr. Meijer guides us through the world of recursive functions. In Haskell, functions can be defined in terms of themselves.  Such functions are called recursive. For example:  factorial 0 = 1 factorial (n+1) = (n+1) * factorial n factorial maps 0 to 1, and any other positive integer to the product of itself and the factorial of its predecessor. Some functions, such as factorial, are simpler to define in terms of other functions. As we shall see, however, many functions can naturally be defined in terms of themselves. Properties of functions defined using recursion can be proved using the simple but powerful mathematical technique of induction. You should watch these in sequence (or skip around depending on your curent level of knowledge in this domain): Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5 Now, we do have a textbook and you should go buy it: The great Graham Hutton's Programming in Haskell. We worked with the publisher, Cambridge University Press, to get all Niners a 20% discount on the book. Now, you don't need the book to learn a great deal from this lecture series since Graham's website has all the slides and samples from the book as well as answers to the exercises. That said, it's highly recommended reading and you should consider it. The promotion code is 09HASK and it is vaild on both the Hardback: 9780521871723 and Paperback: 9780521692694. The catalog pages are: Hardback: http://www.cambridge.org/us/catalogue/catalogue.asp?isbn=9780521871723 and the paperback is: http://www.cambridge.org/us/catalogue/catalogue...