Re: Recursion or interation...??

Pascal Costanza wrote:

    (defun collect-blobs (methods)
      (let ((complete-runs nil)
            (current-run nil))
        (flet ((complete-run ()
          (when current-run
            (push (nreverse current-run) complete-runs)
            (setf current-run nil))))
          (loop for method in methods do
            (when (betap method) (complete-run))
            (push method current-run))
          (complete-run))
        complete-runs))

 
I like this version, and it indeed does what it should. Now I also agree
that it is better understandable than the recursive version. May I use
that code when I decide to make the original code publicly available?

Testing:

(defun betap (x) (oddp x))

(collect-blobs '(0 0 2 3 3 4 6 8 5 5 22 24 25 27))
  ===>
((27) (25) (5 22 24) (5) (3 4 6 8) (3) (0 0 2))

Begin a new group when an element satisfies betap.


;; Start a new sublist when "pred" yields true.
(define (subdivide lst pred)
  (map reverse
    (reverse
      (fold
        (lambda (x accum)
          (if (or (null? accum) (pred x))
            (cons (list x) accum)
            (cons (cons x (car accum)) (cdr accum))))
        '()
        lst))))

(subdivide '(9 0 0 2 3 3 4 6 8 5 5 22 24 25 27) odd?)
  ===>
((9 0 0 2) (3) (3 4 6 8) (5) (5 22 24) (25) (27))