I posted on the bug tracker earlier about doing this and now I am actually attempting it. I went to darcs.haskell.org/packages/ and decided arbitrarily to start with Data.Map, which I copied into the packages/ directory in yhc. When I compile it complains about #if preprocessor statements, which enclose GHC specific code and could be commented out but also there is an #include and what looks like a macro that might actually be important. As I understand it the preprocessor is turned off in yhc (thus the error). As far as I can tell nothing else in packages/ uses preprocessor directives. Possibilities: 1) I should enable -cpp specifically for this file or globally for all of yhc, or just for packages/. (I'm not entirely sure how to get scons to do this but I need to take time and read the scons docs.) 2) I should remove and work around the preprocessor directives. If I start making changes how does yhc keep in sync with any changes that are made to the base packages upstream? 3) It doesn't matter. I should do whatever makes me happy. Please advise. Thanks. --Lane (Submitting this a second time because I snagged the moderation filter the first time.)