I definitely do NOT want the index to be an argument to the unfolders. It seems like an extra argument for not much reason. If you want it, keep it in the state. The claim is that most of the time if you are using it, you are just using it, and then you will use tabulate intead, no? As to vector/arrays, you meant, I assume, that the i versions (with integer) did make sense and the others don't, right?