I think its explained here http://docs.racket-lang.org/reference/stx-patterns.html?q=ellipses#(form._((lib._racket/private/stxcase-scheme..rkt)._syntax)) <http://docs.racket-lang.org/reference/stx-patterns.html?q=ellipses#%28form._%28%28lib._racket/private/stxcase-scheme..rkt%29._syntax%29%29>
at (ellipses stat-template), although I find the explanation confusing. Probably an example of (... ...) would be useful there. On 08/03/2012 09:51 PM, Nick Sivo wrote: > Hi Jon, > > Thanks, that works perfectly! > > Did I miss that somewhere in the documentation? I don't recall seeing > an example of it. > > Best, > Nick > > On Thu, Aug 2, 2012 at 11:55 PM, Jon Rafkind <rafk...@cs.utah.edu> wrote: >> To match a literal ellipses in syntax-parse use #:literal [(ellipses ...)] >> and match on the term `ellipses', then to use a literal ellipses in the >> template use (... ...) instead of just ... >> >> It looks like you only want the latter, so >> >> (define-syntax (example stx) >> (syntax-parse stx >> [(_ name:id) #'(define-syntax (name stx) >> (syntax-parse stx >> [(_ args (... ...)) #'(args (... ...)))])])) >> >> On 08/02/2012 11:30 PM, Nick Sivo wrote: >>> Hi, >>> >>> I'm trying to use ... in the inner macro of a macro defining macro, >>> but can't figure out the right way to escape it. >>> >>> Here's a minimal (pointless) example: >>> >>> (require (for-syntax syntax/parse)) >>> >>> (define-syntax (example stx) >>> (syntax-parse >>> stx >>> ;#:literals (...) ; Doesn't help :( >>> [(_ name:id) >>> #'(define-syntax (name stx) >>> (syntax-parse >>> stx >>> [(_ args ...) #'(args ...)]))])) >>> >>> The goal is to have (example invisible) define a macro called >>> invisible that erases itself. >>> >>> Any ideas? The full code I'm trying to enable follows below if you'd >>> like more context. >>> >>> Thanks, >>> Nick >>> >>> #lang racket >>> >>> (require (for-syntax syntax/parse) >>> racket/splicing) >>> >>> ;;; >>> ;;; Procedure Application >>> ;;; >>> >>> (define arc-nil #f) >>> >>> (define-syntax (arc-#%app stx) >>> (syntax-parse >>> stx >>> [(_ fn:expr arg:expr) >>> #'(let ([efn fn]) >>> (cond [(procedure? efn) (#%app efn arg)] >>> [(pair? efn) (#%app list-ref efn arg)] >>> [(string? efn) (#%app string-ref efn arg)] >>> [(hash? efn) (#%app hash-ref efn arg arc-nil)] >>> [else (#%app efn arg)]))] >>> [(_ fn:expr arg1:expr arg2:expr) >>> #'(let ([efn fn]) >>> (if (hash? efn) >>> ; Have to use the lamda in case arg2 is a function >>> ; See hash-ref docs for more info >>> (#%app hash-ref fn arg1 (lambda () arg2)) >>> (#%app fn arg1 arg2)))] >>> [(_ args ...) >>> #'(#%app args ...)])) >>> >>> ; This allows cross module mutation of globals >>> (define-syntax (declare-with-set-transformer stx) >>> (syntax-parse >>> stx >>> ;#:literals (...) ; Doesn't help :( >>> [(_ var:id) >>> #'(declare-with-set-transformer var (gensym 'unintialized))] >>> [(_ var:id init-val:expr) >>> (let ([store-name (gensym (syntax->datum #'var))]) >>> #`(begin >>> (define #,store-name init-val) >>> (splicing-let ([set (lambda (val) >>> (set! #,store-name val))]) >>> (define-syntax var >>> (make-set!-transformer >>> (lambda (stx) >>> (syntax-case stx (set!) >>> [(set! id val) #'(set val)] >>> ; Uses Racket's #%app, which doesn't work for arc >>> [(id . args) #'(#,store-name . args)] ; function >>> application >>> ; Obviously invalid syntax >>> ;[(id . args) #'(arc-#%app #,store-name . args)] >>> ; Errors because ... isn't recognized as a literal >>> ;[(id args ...) #'(arc-#%app #,store-name args ...)] >>> [id (identifier? #'id) #'#,store-name])))))))])) >>> >>> ; Demo of what I'm looking for >>> (define test (make-hash)) >>> (hash-set! test 'key 'value) >>> (displayln (arc-#%app test 'key)) >>> >>> ; Example of what doesn't work right now >>> (declare-with-set-transformer test2 (make-hash)) >>> (hash-set! test2 'key 'value) >>> (displayln (test2 'key)) >>> ____________________ >>> Racket Users list: >>> http://lists.racket-lang.org/users >> ____________________ >> Racket Users list: >> http://lists.racket-lang.org/users
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