[plt-scheme] macro-generating macros and the bizarre properties of syntax-local-get-shadower

Dimitris Vyzovitis skrev:
> Can someone explain this:
> (module bar mzscheme
>   (begin-for-syntax
>     (define (make-foos)
>       (let ((lst (generate-temporaries (list 'foo 'foocheck 'foov))))
>         (printf "temps:~a~n" (map syntax-object->datum lst))
>         lst)))
> 
>   (define-syntax (define-foo1 stx)
>     (syntax-case stx ()
>       ((_ val)
>        (let-values (((foo foocheck foov) (apply values (make-foos))))
>          (syntax-local-introduce
>           #`(begin (define-syntax #,foo val)
>                    (define-syntax (#,foocheck stx)
>                      (let ((#,foov (syntax-local-value (quote-syntax #,foo))))
>                        (quasisyntax #,#,foov)))
>                    (provide #,foo #,foocheck)))))))

I got confused about all the unquote-syntax-es  so there is a version
without. Note that I'm only introducing marks on the
generated indentifiers.

(module bar mzscheme
   (begin-for-syntax
     (define (make-foos)
       (let ((lst (generate-temporaries (list 'foo 'foocheck 'foov))))
         (printf "temps:~a~n" (map syntax-object->datum lst))
         lst)))


   (define-syntax (define-foo1 stx)
     (syntax-case stx ()
       ((_ val)
        (with-syntax (((foo foocheck foov)
                       (map syntax-local-introduce (make-foos))))
          (syntax
           (begin
             (define-syntax foo val)
             (define-syntax (foocheck stx)
               (with-syntax ((foov (syntax-local-value
                                       (quote-syntax foo))))
                  (quasisyntax foov)))
             (provide foo foocheck)))))))

   (define-foo1 2)
   )

(require bar)
(foocheck2)

; evaluates to 2


-- 
Jens Axel Søgaard