There has been much talk recently about the applicability and use of functional programming languages particularly in reference to concurrency of operations benefiting from multi-CPU computing technologies.
I found that to better understand programming in a functional manner I should start with Haskell. Haskell is the most often mentioned reference, the de facto standard, the purist among functional languages that implement, fully or partially, Lambda Calculus, a kind of computational algebra introduced by Alonzo Church, Haskell Curry and others back in the 1930s.
Included below are references to the material I found most helpful in my quest to understand and use functional programming languages.
- Functional Programming. A good place to start is the definition of functional programming found in Wikipedia. Although this video is about Clojure, I find it a very good reference explaining what makes a language functional.
- Haskell. I used this tutorial to learn Haskell. I found it a valuable reference to learn the concepts behind functional programming.
- Clojure. Clojure is a Lisp-like language that uses the Java JVM for run-time. The more I study it, the more I find it useful, simple, concise. The Clojure Home site and these videos, ten in total, were a great help. Should you want more detail, this video and this article are very useful in learning the language. This blog includes several useful Clojure links. Also, Sean Devlin has several informative videos should you be captivated by the power and elegance of Clojure.
- Scala. Scala is a mix of functional and object-oriented, e.g. C++, Java, Python and Microsoft's C#. Like Clojure, Scala uses the Java JVM for run-time. Although I find Clojure's syntax cleaner, concise, should I say elegant, I feel much more at home when using Scala, at least for now and likely the byproduct of working with non-functional languages; Scala is both functional and object-oriented. The place to start is the Scala Home site and this set of Scala reference links. This presentation by the creator of Scala, Martin Odersky, offers a good introduction to the language. Here is part-2 of Martin's presentation.
- Functional Languages and Concurrency. This short video offers an informal insight as to why functional programming implementations are needed to achieve scalability and concurrency.
The next few years will show whether functional programming languages address these needs, namely productivity, scalability and concurrency, and hence adopted in volume by business applications.
Note that Microsoft has a contribution to functional languages in the form of F#. I had a look at F# and indeed looks interesting; I will look at it in more detail; here are some references I found useful:
For a lighter look at functional programming, To Mock a Mockingbird: And Other Logic Puzzles offers and excellent introduction to the subject.
