Hmm. How big is the change to ac.scm? We've already made at least one rather serious change to ac.scm on the arc-wiki.git (the define-your-own-object-in-functional-position thing), I wonder how much ac.scm will eventually change.
One of the changes is that mzscheme's FFI import a few names starting with an underscore, thus clashing with Arc's namespace. I modified ac.scm so that Arc's names start with a double underscore.
The other problem is that the mzscheme type #<cpointer> is not recognized by Arc : I had to change ac-type so as to add it.
