Review: Introduction to Functional Programming (edX)

I just finished the last problem set in Erik Meijer’s online course Introduction to Functional Programming. This seems like a good opportunity to briefly reflect on it. There aren’t a lot of functional programming MOOCs available. I’m only aware of two Coursera courses, one on FP in Scala, and another on FRP in Akka. While Erik Meijer repeatedly made the point that his course was not on Haskell but on FP in general, there most certainly was a strong focus on exploring functional programming with Haskell.

The recommended course literature was Graham Hutton’s Programming in Haskell, which is incidentally the same book I used when I took a similar course at university. As far as programming-related textbooks go, Hutton’s book is among the best, as he explains topics concisely, and poses carefully selected exercises to the reader. It’s the exact opposite of your typical Java or Python textbook, or the, in my opinion, highly overrated “Learn you a (Haskell|Erlang) for Great Good” books, but that may be a topic for another article.

If you just used the textbook, you’d be well-prepared for the homework exercises and labs already. Still, I enjoyed Erik Meijer’s presentation, and his sometimes quirky remarks, such as that he wants his students to “think like a fundamentalist and code like a hacker”. In special “jam sessions” he demonstrated functional programming concepts in other languages, such as Scala, Dart, Hack, and Kotlin. What I also liked was that some of the labs were offered in several programming languages. The very first lab was offered in Haskell, Groovy, F#, Frege (!), and Ruby, for instance, which led me to playing around with some new languages.

This course is certainly, for the most part, comparable to a university-level course in functional programming. I do have some gripes with the form of the assessment, though. For instance, a common type of question asked you to indicate which of a given number of alternative function definitions were valid. Sometimes the code was obfuscated, and since you couldn’t just copy and paste it, it could easily happen that a GHCi error message was due to a mistake you made while copying the program. This might not have been a problem if those questions had been rare, but because there were so many of them, the tedium was palpable. In later weeks I skipped those questions since I saw very little educational value in them.

Further, the labs were a bit too straight-forward for my taste, but that may be a limitation of the MOOC format. The advice “follow the types” was repeated like a mantra. It is of course a good idea to use type signatures as a guide. However, being given a template that contains correct type signatures and that only requires one to write a few lines of code — if I’m not mistaken, in some weeks the labs required just about a dozen lines of Haskell in total — seems partly misguided. Obviously, it is much more difficult to design a program yourself, and define the correct type signatures. Merely filling in function definitions, on the other hand, is somewhat akin to painting by numbers. It might therefore be a good idea to add a peer-reviewed project to this course in its next iteration. My experience with peer-review on MOOCs is mixed, but it’s better than nothing. After all, the theory behind FP is sufficiently covered. It’s just that the course doesn’t require writing a lot of code, which could only be excused on the labs that focus on type classes and monads.

Overall, Introduction to Functional Programming is a very good course. However, if you’re taking it as a novice, you might want to do the exercises in Hutton’s book in order to get more practice with programming in Haskell.

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