02 March 2014

It is now two months since I started learning Haskell, primarily by solving Project Euler problems and reading Learn You a Haskell for Great Good. With now a little more than 30 solutions implemented in Haskell, out of the 90 that I’ve solved so far, I’m becoming more familiar with the language. After a four-year break in solving Project Euler, this fresh restart has been mind opening.

The last period during which I regularily solved problems, I was using Clojure, transitioning from using Ruby with which I had implemented my first 60~ solutions. As a starting point to learn Haskell, I thought it would be a good idea to try porting the code from my solutions originally implemented in Clojure. I soon realized the code I wrote at that time was quite difficult to understand, and the problem was recursion: a good part of the algorithms were implemented with explicit recusion using the loop construct

Recursion may well be one of the functional programming foundations, but it seems to sometimes make algorithms even more difficult to understand than data mutating for-loops in imperative programming languages.

After starting to implement new solutions for unsolved problems, I’ve found that Haskell made it really easy to avoid explicit recursion to write complex algorithms, by instead using higher order functions such as map, foldl, filter, scanl, groupBy, zipWith, and other list combinators.

The fact that functions are curried by default also allows to chain composed functions in a very succinct way as opposed to Clojure in which one would have to use partial in order to curry functions, or write anonymous functions.

All this conforts me in thinking that Haskell is a very good language to implement functional algorithms using elegant abstractions.

Finally, I’ve found that the performance of Haskell was better and far more predictable than Clojure, allowing to spend more time focusing on algorithms core logic rather than implementation details and performance tuning, which Clojure dynamic nature makes quite obscure.

This said, I’d really like to soon move on some real world project to get a better idea of what it is to develop software with Haskell.

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