Comment by cubefox
1 year ago
I always thought the problem with a "purely" functional view is much more practical: From my limited Haskell experience, I gather that you have to use recursion instead of loops, since loops (and GOTOs) work by iteratively modifying some state, unlike recursion. But humans think in loops. If you look in a cookbook for a recipe, it will almost certainly contain loops and rarely any recursions.
Recursion programs are provably Turing equivalent to WHILE or GOTO programs, but that doesn't mean they are equally natural for our brain to think about. (Not to mention things like tail recursion, which is even less intuitive.)
I definitely don't think in terms of recursion (and I don't think I've seen it explicitly in a recipe!), but I'm not sure loops and interation are necessarily that intuitive, either. I learned programming at an early age and I still distinctly remember the period when loop constructs "made sense".
I can believe that recursion is even less easy to teach than iteration, but it may be that this is a pedagological issue, or that we have yet to work out the best way to convey or document computation.
Many recipes contain WHILE loops. E.g. while the pan is not full, layer meat sauce, lasagna noodles, and bechamel sauce. FOR loops (do the x process 10 times, or once for everything in a list) are also prefectly natural. Examples for recursion are not as easy to find. This points to recursion itself being harder for us than loops. Understanding loops in recipes doesn't require pedagogical attention.