An example of fast numerical computation using Haskell 13 years ago
Agreed. Optimizing the code without first fixing the asymptotic performance of the algorithm detracts significantly from the article. I've solved this problem before in Project Euler, in both Haskell and C++, and for my purposes as a beginning Haskell programmer, figuring out how to construct an asymptotically efficient algorithm for a Dynamic Programming problem in Haskell is what is interesting here.