Functional programming is a programming paradigm where computation is meant as the evaluation of mathematical functions. State and mutable data are avoided . It emphasizes the application of functions, in contrast to the imperative programming style, which emphasizes changes in state. This paradigm has its roots in lambda calculus which is a formalism used to investigate function definition, function application, and recursion. Many functional programming languages can be viewed as extensions to the lambda calculus.

The best way to start learning functional programming is by writting your own simple programs taken from simple books. In this page I will describe some great resources to start with.

This is a very good book for a beginner since only good knowledge of C# is required. No prior knowledge of F# or functional programming is needed to start learning. It clearly provides examples that explain how functional programming changes from the other paradigms. The only thing you need to know is basic programming.

This book is great because it presents data structures from the point of view of functional languages and anyone with basic programming knowledge (C, C++ or Java) programmers should be able to implement data structures in a functional perspective.

I fould this book very useful. It teaches the functional programming language Haskell which is the most modern version of the Lisp family. The is is a pleasure to read and easy to understand.

This is a classic book on Artificial Intelligence and LISP. It shows through examples how to solve AI problems using functional languages. I strongly recommend it.

This is another very good book that teaches the basic concepts of functional programming. It explains allo through the CAML language and it is very nice to read.