Re: define-syntax can only be used with local variables

[Philippe de Rochambeau <phiroc@free.fr>]

I get (1) :

(define-syntax nil2!
    (syntax-rules ()
        ((_ x)
            (set! x '(0)))))


#|kawa:1|# (load "define2.scm")
#|kawa:2|# (define y '(1))
#|kawa:3|# y
(1)
#|kawa:4|# (nil2! y)
#|kawa:5|# y
(1)
#|kawa:6|# 

I am using Kawa 3.1.1 on Macosx.

Philippe


> Le 14 sept. 2021 à 14:42, Damien Mattei <damien.mattei@gmail.com> a écrit :
> 
> i have test one of your example and it works fine on my system:
> mattei@moita ~]$ kawa
> #|kawa:1|# (define-syntax nil2!
>     (syntax-rules ()
>         ((_ x)
>             (set! x '(0)))))
> #|(---:2|# #|(---:3|# #|(---:4|# #|kawa:5|# 
> #|kawa:6|# (define y '(1))
> (nil2! y)
> (display y) (newline)#|kawa:7|# #|kawa:8|# 
> (0)
> #|kawa:9|# y
> (0)
> 
> Damien
> 
> On Fri, Sep 10, 2021 at 9:34 AM phiroc--- via Kawa <kawa@sourceware.org <mailto:kawa@sourceware.org>> wrote:
> Hello,
> in the below code, nil! and nil2! only set variables values to '() and '(0) when such variables are local (let).
> When I run the code with LispKit Go Scheme, global variables (such as y below) are also set.
> What gives?
> Many thanks.
> Philippe
> 
> 
> 
> ;;
> ;; ..\bin\kawa -C .\javafx0.scm
> ;; java -cp "..\lib\kawa.jar;." javafx0
> 
> (let ((x '(1 2 3))) 
>     (define-syntax nil!
>         (syntax-rules ()
>             ((_ x)
>                 (set! x '()))))
>         (nil! x) (newline) (display x) (newline))
> 
> (define-syntax nil2!
>     (syntax-rules ()
>         ((_ x)
>             (set! x '(0)))))
> 
> (let ((x2 '(4 5 6)))
>     (nil2! x2)
>     (display x2) (newline))
> 
> (define y '(1))
> (nil2! y)
> (display y) (newline)
> 
> (define (f-nil! x)
>     (set! x '()))
> 
> (define z 4)
> (f-nil! z)
> (display z)