If you used something like CLN (http://www.ginac.de/CLN/) then you could get the full numeric tower basically for free. But perhaps you'd rather implement numbers in Arc instead.
As you probably know, I submitted a GSoC proposal for CL-Arc. I could write up a quick proposal for Arc-C, but there are only two more days before applications are due. Also, someone from the Arc community would need to apply to mentor the project in order for it to be funded.
I've taken a look at CLN and it seems to be a C++ library. I suppose this means we need to create some sort of set of wrapper functions and wrapper data types to handle this for us.
Also since allocation is all from the heap it seems we can use Boehm GC. Limited stack allocations (for leaf functions) would be cool too ^^. Edit: Oops. Since we don't actually end the function until at HALT(), it seems we can't free memory allocated via alloca().
"Google does not have specific eligibility requirements for mentors, as we know our mentoring organizations will be best able to determine the selection criteria for their mentors."
I don't know if LispNYC has any specific requirements.
As a mentor, I think you have to be in email contact with your student, give them advice as necessary, and evaluate their work. I believe I read somewhere that they estimate mentoring will take about 5 hours a week depending on the number and difficulty of projects.
If there's no need to be physically there, I'm willing to mentor you, in case sacado is somehow disqualified or is otherwise unable to mentor you (I'll probably ask sacado to unofficially mentor my mentoring you, though, sort of a meta-mentor). Anyway I've just applied, although I'll gladly defer to sacado (it'll be mostly his code anyway) if he is able to mentor you.
Note that due to various circumstances, I won't be able to leave my country until about a year or so, so if my physical presence is needed, sorry!
Ok, I submitted my proposal to GSoC. If you'd like to mentor, I would appreciate it. (Otherwise I can't get funded.) And please note that if you want to mentor, you need to apply today, or tomorrow (March 31) before 5:00 PM PDT.