A recent question on Stack Overflow got me thinking about how to turn a recursive algorithm into an iterative one, and it turns out that Python is a pretty decent language for this.

Of course, the technique that I’m going to show you is not necessarily “Pythonic”. There are probably more Pythonic solutions using generators and so on. What I’d like to show here is that to remove this sort of recursion, you can do so by re-organizing the code using a series of small, careful refactorings until the program is in a form where removing the recursion is easy. Let’s see first how to get the program into that form.

And part 2: https://ericlippert.com/2018/12/17/removing-a-recursion-in-python-part-2/

Today I want to look at a rather different technique for removing a recursion, called continuation passing style. Long-time readers will recall that I discussed this technique in Javascript back in the early days of this blog, and that a variation on CPS is the mechanism that underlies async/await in C#.