For future reference, you should try the wonderful macro stepper in DrRacket, which shows you exactly how expansion happens. It can even handle buggy, non-terminating examples like the version of `test` you wrote. -Philip
On Wed, Aug 29, 2018 at 7:20 AM Philip McGrath <phi...@philipmcgrath.com> wrote: > I'm not familiar with how `ir-macro-transformer` is supposed to work, but > your macro is currently fails for essentially the same reason as: > (define-syntax (diverge stx) > stx > > The `expr` given to `test` is a syntactic list beginning with the > identifier `test`, so including it in the output triggers another expansion > of `test`, infinitely. > > -Philip > > > On Wed, Aug 29, 2018 at 7:06 AM t791bc via Racket Users < > racket-users@googlegroups.com> wrote: > >> Hi, >> >> while syntax-case has some advantages, I was trying to implement a >> Chicken style ir-macro-transformer in Racket so that I can write macros >> that will run both on Racket and systems like Chicken/Chibi Scheme. >> >> My first attempt was as follows: >> >> (begin-for-syntax >> (require (for-syntax racket/base)) >> (define-syntax (ir-macro-transformer stx) >> (syntax-case stx () >> [(_ ir-trans) >> #'(lambda (x) >> #`(ir-trans #,(syntax->datum x) 23))]))) >> >> (define-syntax test >> (ir-macro-transformer >> (lambda (expr inject) >> expr))) >> >> The result was "Background expansion terminated abnormally (out of >> memory)". If the #, is taken out I get an error that x is unbound. As >> should be obvious from the above, I find it hard to reason about all those >> syntax effects - which only makes me want the ir-macro-transformer more >> despite all its shortcomings. >> >> Any help would be highly appreciated. >> >> >> -- >> 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.
