On Aug 6, 2014, at 1:47 PM, Alexander D. Knauth <[email protected]> wrote:
> > > On Aug 6, 2014, at 1:10 PM, Kevin Forchione <[email protected]> wrote: > >> >> On Aug 5, 2014, at 2:21 PM, Jens Axel Søgaard <[email protected]> wrote: >> >>> Is this a step in the right direction? >>> >>> (define-syntax (x stx) >>> (syntax-parse stx >>> [(_ (y ... (z ...) w ...)) >>> #'(xf (yf y ... (zf z ...) w ...))])) >>> >>> The pattern (z ...) ... will match a sequence of lists such as (4 5 6) (7 8) >>> but it won't match (4 5 6) 7 8 from your example. >>> >>> /Jens Axel >> >> Closer. It doesn’t match something like ‘( 1 2 3 (4 5 6) 7 (8 9) 10), for >> instance. > > For that I think you want something like this: > (syntax-parse stx > [(_ (~or (z ...) > y) > ...) > #'(xf (yf y ... (zf z ...)))]) Sorry I forgot an ellipsis. I meant this: (syntax-parse stx [(_ (~or (z ...) y) ...) #'(xf (yf y ... (zf z ...) ...))]) > > Either that or you can use my version of syntax-parse with pattern-expanders > and use ~seq-no-order: > https://github.com/AlexKnauth/seq-no-order > >> >> I have tried: >> >> #lang racket >> >> (require (for-syntax syntax/parse)) >> >> (define-syntax (x stx) >> >> (define-syntax-class binding >> #:description "binding list" >> (pattern (z:id ...))) >> >> (define-syntax-class or-binding >> #:description "binding or" >> (pattern (~or zb:binding y:id) >> #:with (z ...) #'(zb.z ...))) > > This won’t work because if the y:id pattern matches instead of the zb:binding > pattern, then the zb.z attribute won’t be there. > Instead you probably wan’t this: > (define-syntax-class or-binding > #:description "binding or" > (pattern zb:binding > #:with (z ...) #'(zb.z ...)) > (pattern y:id > #:with (z ...) #'(y)) ; or whatever, depending on what you want > to do here > ) > >> >> (syntax-parse stx >> [(_ (ob:or-binding ...) ...) >> #''ok >> #;#'(xf (yf ob.y ...) ...) >> #;#'(xf (yf ob.y ... (zf ob.z ...) ...) ...)])) >> >> (define (xf . xs) xs) >> (define (yf . ys) ys) >> (define (zf . zs) zs) >> >> (x (a)) >> (x (a b (c))) >> (x (a b c (d e f) g h)) >> >> But while the pattern “appears” to match, I can’t seem to construct a >> template that is acceptable to syntax-parse, which doesn’t like the #:with >> clause on my syntax-class or-binding. I must be missing something. >> >> -Kevin >> >> >> ____________________ >> Racket Users list: >> http://lists.racket-lang.org/users >
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