Hi Brian, Sorry for the delayed response.
My goal is to write a program GhcRemake that works like "ghc --make." However, instead of terminating after compilation is done, I want the program to stay open and wait for me to hit <ENTER>. When I hit <ENTER>, GhcRemake rebuilds the project, just as if I had called "ghc --make" again with the same arguments. The benefit of such a program is that GhcRemake should be able to cache a lot of data in memory between invocations and hopefully be able to do the subsequent re-makes much faster.
Nice idea!
My program seems to work fine when run on itself and when run on Cabal. But, these two packages seem to be too small to notice any reduction of building time. So, I decided to test my program by building the GHC API with it. Unfortunately, it seems like every build after the first one in the session does the dependency analysis badly, and things get recompiled unnecessarily.
It looks like the problem is caused by recursive module imports. I've added a bug (#1027) with a smaller example of it. Thanks Ian