Per the discussion from Friday[1], any function that you can unroll into a (stateless) circuit.
Edit: which, AIUI, means any function where you can a) prove it halts, and b) recursion and loops are converted into loops that execute for a constant number of loops known at compile time.
Edit: which, AIUI, means any function where you can a) prove it halts, and b) recursion and loops are converted into loops that execute for a constant number of loops known at compile time.
[1] https://news.ycombinator.com/item?id=24007566