In wart the name can be nicer still -- just loop since for does what arc's loop does, in the footsteps of classical C.
Edit 20 minutes later: I ended up going with recur instead of next, to form a loop.. recur pair. I also considered with loop.. recur to strengthen the connection with with for the alternating var/val syntax. (The other pair of keywords in wart is collect.. yield in place of accum acc.) https://github.com/akkartik/wart/commit/b7b822f4fb has has an example use, which had me hankering for absz's w/afn (though with a better name; http://arclanguage.org/item?id=10125)
Edit 25 minutes later: It turns out xloop nests surprisingly cleanly. This does what you expect:
loop (a 0)
loop (b 0)
prn a " " b
if (b < 5) (recur ++b)
if (a < 5) (recur ++a)
Edit 29 minutes later: Oh, loop.. recur is precisely what clojure uses!