Faster graph SCCs

Hi, I have implemented Tarjan's algorithm for computing the strongly connected components of a graph. It is considerably faster then what's available in the "containers" package for larger graphs (see the attached picture). It would be nice to replace the existing implementation in the containers package, but I though that I'd check with the mailing list before I do this. If you want to try it out, I have put the code on hackage: http://hackage.haskell.org/cgi-bin/hackage-scripts/package/GraphSCC -Iavor