You do not need gensyms if you try to mimic or implement my suggested #. . On the other hand when if you do this
(define (f stx) #`(let ((x 1)) #,stx)) and use this with #`(let ((x 2)) #,(f #'x)) the resulting expanded code would produce 1 which is not what you want. So in the racket matcher I wrote I needed to do (with-syntax ((x (datum->syntax stx (gensym "x")))) #`(let ((x 2)) #,(f #'x)))))) Hope that this makes things clear! /Stefan On Tue, Jul 3, 2012 at 11:33 PM, Ludovic Courtès <l...@gnu.org> wrote: > Hey! > > Stefan Israelsson Tampe <stefan.ita...@gmail.com> skribis: > > >> Stefan Israelsson Tampe <stefan.ita...@gmail.com> skribis: > >> > >> > Maybe this help to see what I'm after, > >> > > >> > #'(let ((x v)) #.(f #'x)) > >> > > >> > <=> > >> > > >> > (let-syntax ((g (lambda (stx) (syntax-case stx ((_ x) (f #'x))))) > >> > #'(let ((x v)) (g x)) > > [...] > > > If you want to try another path using functions in stead of macros and > > working hard with #, and #,@ > > you will for complex macros like a matcher need to gensym by hand or > > destroy the readability of the > > code. As illustrated by the simple example above. > > Hmm, the example above does not use gensym. What am I missing? > > Ludo’. >
