[Note: Like functions, hash tables can't be printed out in a way
that can be read back in. We hope to fix that though.]
The problem that I see with macros+hashtables in macroexpansion, as well as with printing/reading-back-in functions+macros+hashtables, is that currently an expression is compiled, before it is evaled, and loses its original uncompiled form. That's why macros are currently not truly first-class.
If used with eval or in macroexpansions this only causes a problem with macros and hashtables, not with functions or hashtables used as functions. Like nlavine pointed out, it only takes an additional line of code in "ac" to make your example work.
