Re: Collection utilities

B. Pym wrote:

  * (with-collectors (foo)
      (loop for pos upfrom 1
            for l in '((a b c) (one two three) (you and me) (girl))
            do (collect pos :into foo)
            do (loop for sym in l
                     do (collect pos :into foo))
            finally (return foo)))
  (1 A B C 2 ONE TWO THREE 3 YOU AND ME 4 GIRL)

 
;;; Or....
 
* (loop for pos upfrom 1
      for l in '((a b c) (one two three) (you and me) (girl))
      collect pos
      append l)
(1 A B C 2 ONE TWO THREE 3 YOU AND ME 4 GIRL)

 
Gauche Scheme
 
(append-map
  cons
  (lrange 1)  ;; Infinite but lazy.
  '((a b c) (one two three) (you and me) (girl)))
 
  ===>
(1 a b c 2 one two three 3 you and me 4 girl)

Another way:

(concatenate (map-with-index cons
  '((a b c) (one two three) (you and me) (girl))))

  ===>
(0 a b c 1 one two three 2 you and me 3 girl)