I suppose Qi's greatest "innovation" is their datatyping scheme which allows the definition of datatypes based on C. A. R. Hoare's Sequential Calculus. I haven't read the paper; but I suppose it might be worth looking into. Basically, it's defining a datatype based on a set of rules.
I'm not sure how useful it would be in Arc, Qi and Arc have very different goals. Qi tends toward functional programs and often breaks away from lispyness, while Arc holds simplicity and elegance up as its goals. Arc also wants to stay lispy, albeit adding a few useful shortcuts (though I'm still on the fence with the new .! syntax). Personally, speaking, I don't see the datatypes Qi has as particularly useful unless you also adopt some sort of static typing scheme as well and I'm pretty sure one of Arc's goals is NOT to do that.
Implicit Function Currying is also allowed by Qi. It's useful in some cases and wouldn't HURT adding to the code; though the people who seem to be saying it would dramatically improve the brevity of Arc code are overestimating its effect; Arc has a lot of optional parameters which could make currying useless for a lot of the places it is used in Qi. For example, (+ 4) which curries an addition operating to the next number that is passed to it. In Arc, this is would return 4. I'm unconfident about which way is the right way.
Qi is certainly a decent language for Functional Programming Enthusiasts but doesn't have a lot to offer Arc. Maybe their new class system which is coming around in Qi II would be useful to adopt, but I'm afraid I've never seen it in action myself so I'm unsure of its usefulness.
Something very useful, which you might consider adding to the standard is something similar to Kenny Tilton's Cells. I'd be interested in seeing how someone would adopt Cells to use in, say, a web application. It could be very useful.
I am working on a "lite" version of Cells for Arc as we speak
(rough start here http://common-lisp.net/cgi-bin/viewcvs.cgi/kennysarc2/cells-...) and I do think a logical step after that would be exploration of applying that to a web app. Unfortunately I have not mucked with interwebby programming so I really would not know where to start. And it might make more sense for me to start with a Common Lisp library such as Hunchentoot. Stay tuned.
Wow Cells! All right, I just heard a lot of enthusiasm for Cells on c.l.l but never managed to grok much of it (insufficient docs IMO); it would be interesting how you handle the mutation of objects - there's no hook in Arc for that yet.
From the looks of this framework it's a test specification.
Incidentally, arc.arc already defines an (obj ...) macro. Do you intend to redefine it?
Thanks, but I think all the enthusiasm on c.l.l is from me. :) Maybe when I provide a Web app example people will get fired up. (I am a dinosaur, thought a desktop GUI would do the trick);
http://common-lisp.net/project/cells-gtk/
As for controlling change, right, my-obj!my-slot will be a backdoor, Arcells (name?) will have to work via readers/writers that invoke the Arcells engine.
Framework? Test spec? What I have so far is merely motivational examples (and I am using the OBJ macro, not redefining it):
http://smuglispweeny.blogspot.com
Look for (+ Arc Cells) Baby Steps, which I am mopping up once the caffeine hits my cortex. When done I'll submit a new thread.
