Here are the changes I needed to make in order to get Omega to compile with ghc-6.6.

Changlog entry:

18Oct2006  Greg Buchholz 

  * DepthFirstSearch.hs : Changed from using the ST module to Control.Monad.ST
                          and Data.Array.ST
  * Infer2.hs : Modified to use Data.Map instead of deprecated Date.FiniteMap
  * Toplevel.hs : Modified to use Data.Map 
  * Makefile : Get rid of ghc-6.4 specific "-package lang", let "-make"
               figure it out for us.

...and the diffs.