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From: HenHanna <HenHanna@dev.null>
Newsgroups: comp.lang.lisp,comp.lang.scheme
Subject: Re: What's the error in this =?UTF-8?B?bWFjcm8/?=
Date: Tue, 24 Sep 2024 00:49:20 +0000
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On Sat, 21 Sep 2024 13:29:23 +0000, B. Pym wrote:

> KK wrote:
>
>>> (defmacro sum (expression index initial condition)
>>> ;; Sum $expression$ for $index$ = $initial$ and successive integers,
>>> ;; as long as $condition$ holds.
>>>   (let ((temp (gensym)))
>>>     `(do ((,temp 0 (+ ,temp ,expression))
>>>           (,index ,initial (1+ ,index)))
>>>          ((not ,condition) ,temp))))


        This looks good to me...  Was this the corrected version?

>>
>> The main error with this macro is that it does something you could do
>> with the standard LOOP. I.e. instead of debugging this macro, you could
>> be working on the program where this macro is intended to be used:
>>
>
>>  (loop for x from 1 while (< x 6) summing x)    --> 15
>
> Gauche Scheme
>
> (use srfi-42) ;; sum-ec
> (sum-ec (:range x 1 6) x)        ===>      15


In Scheme and  Gauche Scheme,   do ppl use  Gensym?


(define-macro (Sum expression index initial condition)
              `(do ((%Sum 0 (+ %Sum ,expression))
                    (,index ,initial (+ 1 ,index)))
                 ((not ,condition) %Sum)))

(print (macroexpand '(Sum  x  x 1 (< x 6))))

(print (Sum  x  x 1 (< x 6)))