As a note for other n00bs who want to use the mz patch on anarki, it's probably best to just manually add the one line to the ac.scm file. Running the patch will fail with an error "patch already detected". I'm no unix expert but I looked at the anarki verion and there's already extra lines added where the patch expects to place it's code line(And the "add anyway" unix prompt failed for me).
At any rate I'm now playing with your json library CatDancer. Thanks for the help along the way.
T.
I have no idea why I used ((mz integer?) v) instead of (isa v 'int) in json.arc, it sounds like it would have saved you some trouble if you hadn't needed to install the mz patch first.