Re: Multivalue tail recursion?

Ken Tilton wrote:

Anyway, I whipped one up in a few lines that not only pulls n items
off the list, but it returns the remaining items as well.  Let me know
what you think.  I was kind of surprised that I was able to do it
without the use of an accumulator parameter.
>
(defun first-n (n list)
 "Splits the list after the first n elements"
 (if (= 0 n)
     (values '() list)
     (multiple-value-bind (from-front rest) (first-n (1- n) (rest
list))
       (values (cons (first list) from-front) rest))))

>
>
I would probably do something like this instead:
>
(defun first-n (n list)
  (loop for i below n for (a . d) on list
     collect a into x
     finally (return (values x d))))

 
Niiiiiiice.

Gauche Scheme:

(define (first-n n xs . ys)
  (dotimes (n) (push! ys (pop! xs)))
  (values (reverse ys) xs))