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From: "B. Pym" <Nobody447095@here-nor-there.org>
Newsgroups: comp.lang.lisp
Subject: Re: Simple recursive functions in Lisp
Date: Sun, 14 Jul 2024 19:56:39 -0000 (UTC)
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B. Pym wrote:

> Pascal Bourguignon wrote:
> 
> > (defun sum (list)
> >   (loop :for x :in list :sum x))
> 
> Gauche Scheme
> 
> (define (sum lst)   (fold + 0 lst))
> 
> (sum '(1 3 5 7 9))
>   ===>
> 25

Pascal Bourguignon wrote:

> >> Of course, since LOOP is a higher level abstraction.  You should
> >> compare with this iterative form:
> >>
> >> (defun sum (list)
> >>   (do ((current list (cdr current))
> >>        (sum 0))
> >>       ((null current) sum)
> >>    (setf sum (+ sum (car current)))))

Better:

(define (sum lst)
  (do ((xs lst (cdr xs))
       (res 0 (+ res (car xs))))
    ((null? xs)  res)))