Well I guess you could say the essence of FP is working recursively without (mostly) thinking of it, and not having to deal with the sort of control flow necessary for either loops or the kind of self-administered recursion you seem to think of.
The .join() taking the iterator in their example is, if you look closer, very much a fold/reduce repeatedly invoking a join of the thus far assembled string, the next part, and \n. Recursion!
Also rather than mutable i/j variables being incremented (albeit implicitly so in your example), generating a list of all numbers on which to run.
The .join() taking the iterator in their example is, if you look closer, very much a fold/reduce repeatedly invoking a join of the thus far assembled string, the next part, and \n. Recursion!
Also rather than mutable i/j variables being incremented (albeit implicitly so in your example), generating a list of all numbers on which to run.