My Introduction to Haskell

A few years ago when I was studying for my degree at university, I took a class on functional programming using the Haskell programming language. It was very instructional, if a little abrupt. I struggled with the language initially, despite being very comfortable with a number of other (imperative) languages. Once it started to click, however, I started to get a glimpse of the power must inevitably draw many toward the functional paradigm.

The project we were given was to build on an existing compiler (written in Haskell) for a simple, strictly-typed programming language devised by the lecturer. Once the lexer & parser had been extended with the new features, we also had to generate custom bytecode for the new features. Finally, we had to write an interpreter for the bytecode in C or Java. Compiler development was something I had always felt was out of my reach but the more I toyed with the code, the more comfortable I became with Haskell’s fairly alien syntax and – in turn – with extending the compiler itself.

The Joy of the Functional Paradigm

Within an hour or two, my extensions to the mini-language meant that I could now assign values to variables. Another few hours, and I had a for loop. Another, and I had enumerations and constants. The byte code generator, however, required me to step out of the mindset I had been in for half of the day: How do I now turn the AST generated by the parser into bytecode?

By this stage I was becoming comfortable enough with Haskell that I was able to work out the basics from the code used for the original language constructs. I was beginning to get a rough idea by the end of the first day and another day or two later, the project was finished. Thinking about it now, this was perhaps the only university unit that I really, really enjoyed. It was fun. Haskell and the constructs of the parser framework we were using were powerful tools. I had achieved something completely new and exciting using a language I was almost totally unfamiliar with.

The Return to Functional Languages: Ocaml

Fast forward maybe three years. I haven’t really touched Haskell since. Sure, I tried – but without a practical application for it there was no real drive. The passion I that had grown for compilers led me to the Python source code and, eventually, to PEP 341 where I was able to scratch a long-standing itch in the form of the try/except, try/finally statements. Due to the recent introduction of an AST, the changes were generally limited to the grammar and the AST and – although satisfying – were relatively trivial to implement.

As far as code contributions for Python go, I’m sure that I just need more practice and experience with the source. However, I still long to test the waters with functional languages again. Haskell, while it proved to be powerful and fun, lacks the supporting libraries to make useful (in the short term, anyway) only to academics and those willing to slog it out writing their own support code. Scheme was intriguing, but I’m still not sure which implementation I should be using nor did it have a useful library. Then I started hearing about Ocaml. A powerful functional programming language with support for imperative and/or object-oriented programming, Ocaml also sports a decent (if a little bare and disorganized) framework for all the basics.

A Lack of Tutorials

Documentation for Ocaml’s libraries exist, but tutorials for learning Ocaml properly are few and far between. offers lots of information for those patient enough to read it, but I found it a little hard going.Further, there was little in the way of web, network/socket, graphics and UI programming.

The Big Tutorial Idea

I’m going to try and learn Ocaml myself using whatever resources I can find and hopefully distill the information and knowledge I come across in an easy-to-follow manner. Obviously I’ll be learning as I go, so the more jaded Ocaml and functional programmers should certainly point out the foolish errors of my ways.

Eventually I’d like to compile these posts into a proper tutorial for newcomers to Ocaml – although not necessarily newcomers to programming. From my limited experience with Ocaml, I can already see it’s a powerful language with much to offer. Keep an eye out for part 1 of TMHO later next week! Any suggestions/comments?