Hebert - Learn you some Erlang for great good!: a beginners guide

Learning to program is fun, or at least it should be fun. If its not fun, you wont enjoy doing it. During my career as a programmer, I have taught myself several different programming languages, and it hasnt always been fun. Whether or not learning a language is fun depends to a large extent on how the language is introduced.

When you start working with a new programming language, on the surface it seems that all you are doing is learning a new language. But at a deeper level, you are doing something much more profoundyou are learning a new way of thinking. Its this new way of thinking that is exciting, not the minor details of the punctuation or how the language looks compared to your favorite programming language.

Functional programming is one of those areas of programming that has acquired a reputation for being hard (concurrent programming even more so), and so writing a book about Erlang that covers the ideas of functional programming plus concurrent programming is a daunting prospect. Make no mistake about it: Introducing functional programming is not so easy, and introducing concurrent programming has its difficulties. Doing both with humor and ease requires a very particular kind of talent.

Fred Hebert has shown that he has this talent. He explains complex ideas in a way that makes them seem simple.

One of the biggest barriers to learning Erlang is not so much that the ideas involved are intrinsically difficult but that they are very different from the ideas in most of the other languages that you will have encountered. To learn Erlang, you have to temporarily unlearn what you have learned in other programming languages. Variables in Erlang do not vary. Youre not supposed to program defensively. Processes are really, really cheap, and you can have thousands of them or even millions, if you feel like it. Oh, and then there is the strange syntax. Erlang doesnt look like Java; there are no methods or classes and no objects. And wait a moment... even the equals sign doesnt mean equalsit means match this pattern.

Fred is completely undaunted by these issues; he treats the subject matter with a delicate dry humor and teaches complex subjects in such a way that we forget the complexity.

This is now the fourth major text on Erlang and is a great addition to the Erlang library. But its not only about Erlang. Many of the ideas in Freds book are equally applicable to Haskell or OCaml or F#.

I hope that many of you will enjoy reading Freds book as much as I did and that you find learning Erlang to be an agreeable and thought-provoking process. If you type in the programs in this book and run them as you go along, youll learn even more. Writing programs is much more difficult than reading them, and the first step is just letting your fingers get used to typing in the programs and getting rid of the small syntax errors that inevitably occur. As you get deeper into the book, youll be writing programs that are pretty tricky to write in most other languagesbut hopefully you wont realize this. Soon youll be writing distributed programs. This is when the fun starts...

Thanks, Fred, for a great book.

Joe Armstrong

Stockholm, Sweden

November 6, 2012