Re: [clisp-list] loop for vars on vars

[Bradley R. <bra...@gm...>]

On Fri, 27 Oct 2006 09:07:13 +0200
"Tomas Zellerin" <zel...@gm...> wrote:

> The expansion
> (macroexpand-1 '(loop for i from 0 to 10 for vars on vars do (print
> vars))) shows the reason.
> 
> (MACROLET ((LOOP-FINISH NIL (SYSTEM::LOOP-FINISH-ERROR)))
>  (BLOCK NIL
>   (LET ((I 0))
>    (PROGN
>     (LET ((VARS NIL)) ; <-------- here
>      (LET NIL
>       (LET NIL
>        (MACROLET ((LOOP-FINISH NIL '(GO SYSTEM::END-LOOP)))
>         (TAGBODY (SETQ VARS VARS) SYSTEM::BEGIN-LOOP
>          (WHEN (> I 10) (LOOP-FINISH)) (WHEN (ATOM VARS)
> (LOOP-FINISH)) (PROGN (PROGN (PRINT VARS))) (PSETQ I (+ I 1)) (PSETQ
> VARS (CDR VARS)) (GO SYSTEM::BEGIN-LOOP) SYSTEM::END-LOOP
>          (MACROLET
>           ((LOOP-FINISH NIL (SYSTEM::LOOP-FINISH-WARN)
>             '(GO SYSTEM::END-LOOP)))))))))))))
> 

It doesn't seem to me that that line is necessarily the problem,
although I am not a clisp guru.  In clisp 2.39...

[1]>  (setf vars '(1 2 3 4))
(1 2 3 4)
[2]>  (setf vars1 '(1 2 3 4))
(1 2 3 4)
[3]> (loop for i from 0 to 10 for vars on vars1 do (print vars))

(1 2 3 4) 
(2 3 4) 
(3 4) 
(4) 
NIL

[4]> (macroexpand-1 '(loop for i from 0 to 10 for vars on vars1 do (print vars)))
(MACROLET ((LOOP-FINISH NIL (SYSTEM::LOOP-FINISH-ERROR)))
 (BLOCK NIL
  (LET ((I 0))
   (PROGN
    (LET ((VARS NIL))
     (LET NIL
      (LET NIL
       (MACROLET ((LOOP-FINISH NIL '(GO SYSTEM::END-LOOP)))
        (TAGBODY (SETQ VARS VARS1) SYSTEM::BEGIN-LOOP (WHEN (> I 10) (LOOP-FINISH))
         (WHEN (ATOM VARS) (LOOP-FINISH)) (PROGN (PROGN (PRINT VARS))) (PSETQ I (+ I 1))
         (PSETQ VARS (CDR VARS)) (GO SYSTEM::BEGIN-LOOP) SYSTEM::END-LOOP
         (MACROLET ((LOOP-FINISH NIL (SYSTEM::LOOP-FINISH-WARN) '(GO SYSTEM::END-LOOP))))))))))))) ;
T

Has the same (LET ((VARS NIL)) line but works. Perhaps it is using the
wrong VARS in the (SETQ VARS VARS) segment?