I think you've highlighted at least one gap in Arc's arsenal. Using Arc2:
arc> (ssplit " foo bar ")
Error: "reference to undefined identifier: _ssplit"
You needed to use ssplit, but Arc doesn't have it.
I don't think the importance of string ops should be underestimated. Strings ops are just as essential as numerical ops. A language that cannot effortlessly manipulate strings is a low-level language in my book. If people are supposed to be testing Arc by using it instead of the languages they were using, Arc needs string ops. Can't they be easily lifted from mzscheme?
Remember the thread on implementing Eliza in Lisp and Ruby? No one posted an Arc version.
Oh, sorry, I should have specified: I used Anarki-specific stuff in several places. Mostly the date-manipulation, but also ssplit (I actually hadn't realized that wasn't in arc2. Yikes). Using Anarki, it should work, though.
I totally agree that strings ops are important. If I recall, PG has also said something to this effect, so I wouldn't be surprised if more of them crop up in the next few releases.