Welcome to the club :-) http://www.mail-archive.com/glasgow-haskell-users@haskell.org/msg06012.html I tried Simon's version, but it throws a "Fail: Ix{Int}.index: Index (5) out of range ((0,4))" error. Haven't tracked down the cause yet.

So I guess that the upshot is just that "GHC is slow on this test." Is lazy evaluation what is slowing this down so badly? - Alson