Re: walk through list and add all n'th item

B. Pym wrote:

Wow: loop macro rulez, somehow..
just one correction:
(loop for (a b c d) on (list 1 2 3 4 5 6 7 8) by #'cddddr
      sum a into a-sum
      sum b into b-sum
      sum c into c-sum
      sum d into d-sum
      finally (return (list a-sum b-sum c-sum d-sum)))
Yeah, i might consider this code as beautiful
olivier

 
Gauche Scheme
 
(use gauche.lazy)
(use util.match)
 
(define data (lrange 1 57))
 
(match (lslices data 4)
  [((a b c d) ...)
   (map (cut fold + 0 <>)
     (list a b c d))])
 
(378 392 406 420)

newLISP

(define data (sequence 1 56))

(map (curry apply +) (transpose (explode data 4)))

  ===>
(378 392 406 420)


Another way.

;; Using "apply" for "reduce".  The 3rd argument tells
;; apply how many items to process at a time.
(apply
  (fn (sums) (map + sums $args))
  (cons '(0 0 0 0) data)
  5)

  --->
(378 392 406 420)