Both techniques worked for me! Thanks! I’m not sure why (format-id #’n “foo~a” [syntax-e #’n)) works when (format-id six “foo~a” (syntax-e #’n)) does not though. Apparently I need to look into the differences between the two contexts.
-Kevin > On May 20, 2016, at 2:58 PM, Sam Caldwell <[email protected]> wrote: > > Kevin, > > I have made this exact mistake in the past. The trouble is with the > lexical context being passed to `format-id`. > > (_foo 3) > foo3 > ;; 3 > > Here, _foo is passed the syntax #'(_foo 3), which came from the same > environment as the reference, foo3. > > (foo 3) > foo3 > ;; error ... > > Here, _foo is passed the syntax #'(_foo 3), which was created *by the > foo macro*, in a different context to the foo3 reference. > > The solution is to pass #'n as the first argument to format-id. > Hopefully this explanation made some sense. > > - Sam > > On Fri, May 20, 2016 at 5:36 PM, Kevin Forchione <[email protected] > <mailto:[email protected]>> wrote: > Hi guys, > I’ve been interested in having a macro build a series of defines. So I > decided to start small, trying to get to a macro that would do something like > the following to begin with: > > >(foo 3) > (define foo1 1) > (define foo2 2) > (define foo3 3) > > I start with a macro that appears to do a single define: > > (require (for-syntax racket/syntax)) > > (define-syntax (_foo stx) > (syntax-case stx () > [(_ n) (with-syntax ([id (format-id stx "foo~a" (syntax-e #'n))]) > #'(define id n))])) > > > And this appears to work for (_foo 3) for instance. > > Then I create a macro that calls this macro: > > (define-syntax (foo stx) > (syntax-case stx () > [(foo n0) #'(_foo n0)] > [(foo n0 n ...) #'(begin > (_foo n0) > (foo n ...))])) > > thinking that I could do something like (foo 1 2 3) as an intermediary step. > So I test it with (foo 3) for instance, expecting it to define foo3 and the > macro debugger tells me that it’s created (define foo3 3), but that foo3 is > bound as foo3.0, which is a mystery to me as I thought building the id using > with-syntax and format-id would have sorted the binding for this. > > Looks like I’m at a learning moment…. any explanation why executing (_foo 3) > at the real works and (foo 3) does not? > > Thanks! > -Kevin > > -- > 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 [email protected] > <mailto:racket-users%[email protected]>. > For more options, visit https://groups.google.com/d/optout > <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 [email protected]. For more options, visit https://groups.google.com/d/optout.
