I hacked together a short version of arc-exe.scm that worked just fine importing from ac.scm. The only problem with that version was that it wasn't a module, and thus couldn't be compiled by mzc. I couldn't make it a module because scheme complained when brackets.scm tried to override read and read-syntax. (Apparently overriding imported bindings only works outside modules.) And when I tried to modify or not include brackets.scm, it would complain that it couldn't find the module ac.