@neauoire Doing a bit of pen and paper computing, and I this is probably going to be a very hard problem to solve.
In the most general case, you are asking "does this loop terminate" which can't be solved (halting problem).
It could be possible to define some limited subset of loops that are known to terminate. However, this would require defining "finite data types" in Uxn and enforcing strings/arrays always end and numbers don't under/overflow.
@CapitalEx OOOoooh, I think you're right. I hadn't made the connection with the halting problem, but that's true, I guess a specific type is indeed the solution here.