On Mon, Jun 21, 2010 at 8:58 PM, prad
it seems to me that if we consider the list to be already built, we can apply zip successively to get the next part of it, but if we think recursively we start at the beginning at each recursive level and go nowhere.
That's a funny way to say it : to me recursive thinking has always been about assuming I already have a function that works on smaller (in some sense) cases, writing the function knowing that and then figuring what's the base case we're tending toward and handling it non-recursively. That's what recursion is about for me and I've always found easier to think about it like that rather than always expansing the recursive calls (I also find it easier than thinking iteratively nowadays but YMMV). In other words what you describe as your new method to think about infinite structure is the only way I approach recursion (of structure or functions). I would say it's a perfectly valid approach as long as you don't forget to handle the base case (here it's the explicit definition of the first two elements). -- Jedaï