While the more obvious application of defunctionalization is to avoid stack overflow from using the implicit machine stack, another application is if you want t

While the more obvious application of defunctionalization is to avoid stack overflow from using the implicit machine stack, another application is if you want to make your algorithm asynchronous. In many languages, it's hard to create an asynchronous recursive function that can yield from inside some deep recursion, and then resume later from where it stopped. On the other hand, if your program is rewritten to use an explicit stack plus a state machine then it's trivial to do things like pausing the execution, or printing some debug message between each step.