indicates that it triggers a bug in 6.4.1
Ah, I missed that. For my word counting indexes, I've settled on Data.Map, calculating an Int or Integer hash for each word (depending on word length, which is fixed). I haven't given it nearly the effort the shootout programs have seen, though, so I'm not sure how optimal it is. Other experiences with FiniteMap/Data.Map etc seem to indicate that they are in the same ball park as Python's hashes.
We never pounded on Data.Map, but I suspect it cannot be as bad as Data.Hashtable.
Hmm...perhaps it is worth it, then? The benchmark may specify "hash table", but I think it is fair to interpret it as "associative data structure" - after all, people are using "associative arrays" that (presumably) don't guarantee a hash table underneath, and it can be argued that Data.Map is the canonical way to achieve that in Haskell. -k -- If I haven't seen further, it is by standing in the footprints of giants