As much as I find Haskell elegant for many things, I have to agree. It reminds me of the infamous Haskell "quicksort" which isn't actually quicksort because it's not in place.

I think not every piece of code needs to be hyper-optimised and in those cases, higher-level (declarative) languages where you don't specify every detail of the algorithm can give rise to very elegant code. But writing very performant Haskell code is a bit trickier.

In the anagram case, there's a straightforward O(n) solution where you count the occurrence of each letter in a hash map for both words and compare those. That can be written in Haskell too, of course, but it's not going to be as short.