That is an awesome bug/feature.

To be sure, what you get at that repl isn't pure arc3.1 (at least for now it's not). It's arc3.1 plus anarki's $ minus libs.arc. So since it has $, you can drop to scheme without even exploiting rocketnia's discovery. You just can't do much harm there (at least, you're not supposed to be able to do much harm there, and you just helped me gain a bit of confidence about that).

It does concern me that you're able to see the current directory and version, but I guess as long as you're not able to change anything on the system it might be ok.

(Someone has to try these things out, and it may as well be me, who intends to do no harm, before it's someone else, who might feel mischievous.)