[This is from a paper we’re submitting to the International Conference on Functional Programming (ICFP 2025)] Introduction Recursion and iteration are the Yin and Yang of programming. Conventional languages support both, but tend to favor the Yang – iteration. Java and C, for example, have elaborate while and for statements. But they treat functions as second-class objects that e.g. can’t be returned as results. Python is a bit better. The Yin, we might say, is strong in that one. Even Python, h...