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From: HenHanna <HenHanna@devnull.tb>
Newsgroups: comp.lang.lisp
Subject: Re: Finding Average without using Recusrion only using Prog
Date: Sun, 16 Jun 2024 11:28:23 -0700
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On 6/15/2024 9:39 PM, B. Pym wrote:
>>      (defun avg (args)
>>        (loop for x in args
>>            for l upfrom 1
>>            summing x into tot
>>            finally (return (/ tot l))))
> 
> Gauche Scheme
> 
> (use gauche.collection) ;; fold2
> 
> (define (add&count n sum cnt) (values (+ sum n) (+ cnt 1)))
> 
> (define (avg nums)
>    (apply /
>      (values->list
>        (fold2
>          add&count
>          0 0
>          nums))))
> 
> (avg '(20 30 40 50 60 70 80))     ===>   50


Nice...    Here's a more boring version:


(define (ave x)
   (let ((L (length x)))
     (if (> L 0)
       (/ (fold + 0 x) L))))

(define (Pave x)   (format #t "~%    ~S  ~S  ~%" x (ave x)))

(Pave  '(1 2 3))
(Pave  '(1 2 3 4))
(Pave  '(1))
(Pave  '())