On Nov 9, 2008, at 8:56 AM, marcomaggi wrote:
Help a guy out!
Both because I need it and as an exercise in learning
SYNTAX-CASE I have tried for hours to write a Common
Lisp like DEFINE-MACRO. I could not get around how to
use/modify/whatever:
(define lisp-transformer
(lambda (p)
(lambda (x)
(syntax-case x ()
((keyword . rest)
(datum->syntax (syntax keyword)
(p (syntax->datum x))))))))
Put that definition in a library (lisp-transformer) like:
(library (lisp-transformer)
(export lisp-transformer)
(import (rnrs))
(define lisp-transformer
(lambda (p)
(lambda (x)
(syntax-case x ()
((keyword . rest)
(datum->syntax (syntax keyword)
(p (syntax->datum x)))))))))
then import that library, and do:
> (import (lisp-transformer))
> (define-syntax foo
(lisp-transformer
(lambda (x)
`(cons ,(cadr x) ,(caddr x)))))
> (foo 1 2)
(1 . 2)
> (let ([cons +]) (foo 1 2))
3
If you're going to learn syntax-case, I don't think you should be
doing lisp macros like the one above.
Aziz,,,
