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comp / comp.lang.scheme / Re: What's the error in this macro?

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* Re: What's the error in this macro?B. Pym
`- Re: What's the error in this macro?HenHanna

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Subject: Re: What's the error in this macro?
From: B. Pym
Newsgroups: comp.lang.lisp, comp.lang.scheme
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Date: Sat, 21 Sep 2024 13:29 UTC
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From: Nobody447095@here-nor-there.org (B. Pym)
Newsgroups: comp.lang.lisp,comp.lang.scheme
Subject: Re: What's the error in this macro?
Date: Sat, 21 Sep 2024 13:29:23 -0000 (UTC)
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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))))
>
> 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

Subject: Re: What's the error in this macro?
From: HenHanna
Newsgroups: comp.lang.lisp, comp.lang.scheme
Organization: novaBBS
Date: Tue, 24 Sep 2024 00:49 UTC
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From: HenHanna@dev.null (HenHanna)
Newsgroups: comp.lang.lisp,comp.lang.scheme
Subject: Re: What's the error in this macro?
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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)))

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