Re: [racket-dev] can a syntax-class "inherit" attributes?
You'd have to ask Ryan to be sure, but I think they're pretty stable. I've been using them for some time. Carl Eastlund On Fri, Aug 23, 2013 at 12:53 PM, Stephen Chang wrote: > Ah, thanks. That's exactly what I wanted. > > How stable are these features? Shall I add them to the docs? > > On Fri, Aug 23, 2013 at 12:54 AM, Carl Eastlund wrote: > > Here's how you want to define AorB: > > > > (define-syntax-class AorB #:auto-nested-attributes > > (pattern :A) > > (pattern :B)) > > > > There's two things going on here, both of which I believe are > undocumented, > > sadly. > > > > One is #:auto-nested-attributes, an option that tells AorB that anything > > bound as an attribute by nested sub-patterns in its clauses should > > automatically become an attribute of AorB. > > > > The other is that empty identifier does not add "." to its attribute > names. > > When you bind a with the attribute X, you get A.X, and when you bind b, > you > > get b.X, but when you bind the empty identifier, you just get X. > > > > So now you just have X bound in both clauses, and that's automatically > made > > an attribute of AorB, and it all works like you want. > > > > Carl Eastlund > > > > > > On Fri, Aug 23, 2013 at 12:22 AM, Stephen Chang > wrote: > >> > >> Is there a way for a syntax-class to automatically inherit attributes? > >> > >> For example, the third class below combines the first two. Is there a > >> way to automatically get the attributes from the first two classes in > >> the third one (ie, I want to drop the "#:attr X #'a.X" part in the > >> third class)? > >> > >> #lang racket > >> (require syntax/parse) > >> > >> (define-syntax-class A (pattern (a b) #:attr X #'b)) > >> (define-syntax-class B (pattern (a b c) #:attr X #'c)) > >> (define-syntax-class AorB > >> (pattern a:A #:attr X #'a.X) > >> (pattern b:B #:attr X #'b.X)) > >> > >> (syntax-parse #'(list 1) [ab:AorB (attribute ab.X)]) > >> _ > >> Racket Developers list: > >> http://lists.racket-lang.org/dev > >> > > > > _ Racket Developers list: http://lists.racket-lang.org/dev
Re: [racket-dev] can a syntax-class "inherit" attributes?
Ah, thanks. That's exactly what I wanted. How stable are these features? Shall I add them to the docs? On Fri, Aug 23, 2013 at 12:54 AM, Carl Eastlund wrote: > Here's how you want to define AorB: > > (define-syntax-class AorB #:auto-nested-attributes > (pattern :A) > (pattern :B)) > > There's two things going on here, both of which I believe are undocumented, > sadly. > > One is #:auto-nested-attributes, an option that tells AorB that anything > bound as an attribute by nested sub-patterns in its clauses should > automatically become an attribute of AorB. > > The other is that empty identifier does not add "." to its attribute names. > When you bind a with the attribute X, you get A.X, and when you bind b, you > get b.X, but when you bind the empty identifier, you just get X. > > So now you just have X bound in both clauses, and that's automatically made > an attribute of AorB, and it all works like you want. > > Carl Eastlund > > > On Fri, Aug 23, 2013 at 12:22 AM, Stephen Chang wrote: >> >> Is there a way for a syntax-class to automatically inherit attributes? >> >> For example, the third class below combines the first two. Is there a >> way to automatically get the attributes from the first two classes in >> the third one (ie, I want to drop the "#:attr X #'a.X" part in the >> third class)? >> >> #lang racket >> (require syntax/parse) >> >> (define-syntax-class A (pattern (a b) #:attr X #'b)) >> (define-syntax-class B (pattern (a b c) #:attr X #'c)) >> (define-syntax-class AorB >> (pattern a:A #:attr X #'a.X) >> (pattern b:B #:attr X #'b.X)) >> >> (syntax-parse #'(list 1) [ab:AorB (attribute ab.X)]) >> _ >> Racket Developers list: >> http://lists.racket-lang.org/dev >> > _ Racket Developers list: http://lists.racket-lang.org/dev
Re: [racket-dev] can a syntax-class "inherit" attributes?
Here's how you want to define AorB: (define-syntax-class AorB #:auto-nested-attributes (pattern :A) (pattern :B)) There's two things going on here, both of which I believe are undocumented, sadly. One is #:auto-nested-attributes, an option that tells AorB that anything bound as an attribute by nested sub-patterns in its clauses should automatically become an attribute of AorB. The other is that empty identifier does not add "." to its attribute names. When you bind a with the attribute X, you get A.X, and when you bind b, you get b.X, but when you bind the empty identifier, you just get X. So now you just have X bound in both clauses, and that's automatically made an attribute of AorB, and it all works like you want. Carl Eastlund On Fri, Aug 23, 2013 at 12:22 AM, Stephen Chang wrote: > Is there a way for a syntax-class to automatically inherit attributes? > > For example, the third class below combines the first two. Is there a > way to automatically get the attributes from the first two classes in > the third one (ie, I want to drop the "#:attr X #'a.X" part in the > third class)? > > #lang racket > (require syntax/parse) > > (define-syntax-class A (pattern (a b) #:attr X #'b)) > (define-syntax-class B (pattern (a b c) #:attr X #'c)) > (define-syntax-class AorB > (pattern a:A #:attr X #'a.X) > (pattern b:B #:attr X #'b.X)) > > (syntax-parse #'(list 1) [ab:AorB (attribute ab.X)]) > _ > Racket Developers list: > http://lists.racket-lang.org/dev > > _ Racket Developers list: http://lists.racket-lang.org/dev
[racket-dev] can a syntax-class "inherit" attributes?
Is there a way for a syntax-class to automatically inherit attributes? For example, the third class below combines the first two. Is there a way to automatically get the attributes from the first two classes in the third one (ie, I want to drop the "#:attr X #'a.X" part in the third class)? #lang racket (require syntax/parse) (define-syntax-class A (pattern (a b) #:attr X #'b)) (define-syntax-class B (pattern (a b c) #:attr X #'c)) (define-syntax-class AorB (pattern a:A #:attr X #'a.X) (pattern b:B #:attr X #'b.X)) (syntax-parse #'(list 1) [ab:AorB (attribute ab.X)]) _ Racket Developers list: http://lists.racket-lang.org/dev
