"Can I ask why anarki does not work with mzscheme 372? Arc works with it."

Yeah, I misspoke. I meant that I don't know if anarki works with mzscheme because I haven't tried it in forever and the default anarki instructions are to use racket.

I'm pretty sure it won't work with v372, that's a really old version. I believe pairs used to be mutable by default back then. Or perhaps they were immutable, but that was a big transition and I'm sure there were bugfixes.

And if you're going to install a more recent version of racket, might as well just run racket since it gets the most eyeballs on bugs. The community seems to have converged on racket as well. Testing resources are scarce; easier to just focus on one configuration.