You need to have the lexical context information of x, y, and z come from stx: otherwise, they will be protected by macro expansion (as a matter of hygiene).
Here's one way to do it: > (define-syntax (a stx) > (syntax-parse stx > [(a) > (with-syntax ([x (datum->syntax stx 'x)] > [y (datum->syntax stx 'y)] > [z (datum->syntax stx 'z)]) > #`(begin > (define x 97) > (define y 98) > (define z 99)))])) You may also want to look at format-id. Also, I found Greg Hendershott's *Fear of Macros* ( http://www.greghendershott.com/fear-of-macros/index.html) a useful supplement to the Racket Guide/Reference in understanding the macro system: ch. 4 addresses some of these issues. -Philip On Sun, Feb 5, 2017 at 8:41 PM, <keccak...@gmail.com> wrote: > I must be missing something simple here. > > 229> (define-syntax a (lambda (stx) (syntax-parse stx [(a) #`(begin > (define x 97) (define y 98) (define z 99))]))) > 230>(a) > 231>y > 232; y:undefined; > 233; cannot reference undefined identifier > 234; [,bt for context] > > If the macro is given these ids, like (a x y z), then it will work, but > can't I also pick standard names like this in advance, or is that somehow > fundamentally "unhygienic"? Perhaps I have to generate the names in a place > visible to both the definition and use or something... > > > ## Peter > > -- > You received this message because you are subscribed to the Google Groups > "Racket Users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to racket-users+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
