[marcosdumay]

The problem is that this is not only about Haskell's fundamentals. It's about them being extended with backpack, an extension that very few people use.

And honestly, I don't see the point there either. I know that backpack is meant to solve some problem everybody has, but I haven't been able to fully understand what that problem is. Specifically on this article, I don't see the gain over using a type class.