What's the error in this macro?

[B. Pym]

(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
(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

[HenHanna]

Post by B. Pym

(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?

Post by B. Pym

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
(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)))