I just realized that I think I've been negligent about cloning my data structures before operating on them and have introduced mutation. And since it could be any combination of dozens of places it's gonna be fun tracking it down.

No really, it will be fun. After falling on my face dealing with lazy seqs pretty much anything else will be fun

I'm spoiled by Clojure. I messed up because this isn't something I'm used to having to think about.