Well, to be honest I still don’t understand the difference: they seem to me like two different styles of structuring the same kind of logic. In fact, the linked

Well, to be honest I still don’t understand the difference: they seem to me like two different styles of structuring the same kind of logic. In fact, the linked list example in the referenced article from Mike Innes I don’t find very convincing, stated as it is: I would like to see that example concretely, to understand how the current Julia protocol would fall short there (“leak”). Same for the `zip` example in the OP here: I’m not sure the Python `itr = iterate(xs)` kind of protocol makes it any simpler. But I’m on holiday and cannot try it out right now—I owe you one here :-)