I could even volunteer to try to add these features to GHC, if the team would accept the help. There are still the issues of update-compatibility for the team to deal with, but I stubbornly believe that they won't be that bad. ;)

Of course, if you send us a patch the chances are we'll incorporate it. Adding a -fprelude-is= flag should be less than 50 lines, and don't forget to document it. It shouldn't be too hard to figure out what to do. Just look for where the -fno-implicit-prelude flag turns up for clues, and we'll be happy to answer any questions. Cheers, Simon