Except you can't destructively update it. So it's really more of a global constant. This is an important caveat because it affects locally scoped ts, too.
arc> (= t 1)
Error: "Can't rebind t"
arc> (= nil 1)
Error: "Can't rebind nil"
arc> (let t 4 (+ t 1))
5
arc> (let t 4 (++ t))
Error: "Can't rebind t"
I imagine that's what made it seem reserved. You still probably shouldn't name variables t or nil.
Hmm, good point. Since it does no harm to change t when it is a local variable, I'd remove the restriction for that case.
I might even drop the restriction altogether, as it doesn't seem to have much useful purpose. I can break Arc just as badly by rebinding "car" or other variables, so why this particular effort to keep me from hurting myself?
