Re: [racket-users] Confused about syntax properties
> On 29 Jan 2017, at 11:21, Ben Greenman wrote: > > The third result is #f because in the third example, stx is `(annotate > (annotate 4 2))`. So the first pattern matches and `val` is the syntax > `(annotate 4 2)`. > > You can get a "strict" evaluation order by using `local-expand` inside the > `annotate` macro. For example: > > #lang racket > > (define-syntax (annotate stx) > (syntax-case stx () >[(_ val) ; read >(or (syntax-property (local-expand #'val 'expression #f) 'annotation) > #'#f)] >[(_ val ann) ; write >(syntax-property #'val 'annotation #'ann #t)])) > > (annotate 4) ;; ==> #f > (annotate 1 6) ;; ==> 1 > (annotate (annotate 4 2)) ;; ==> 2 Nice, thanks! I wasn’t aware of that. so macros are expanded in the order that the reader reads them, not in so called evaluation order. -- 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.
[racket-users] Confused about syntax properties
Hullo all, I'm messing around with syntax properties to try to get a feel for them, but in one of my tests they aren't behaving the way I would expect them to. In my example the output is #f 1 #f, when I would have thought it would be #f 1 2. Why is the third result #f and not 2? #lang racket (define-syntax (annotate stx) (syntax-case stx () [(_ val) ; read (or (syntax-property #'val 'annotation) #'#f)] [(_ val ann) ; write (syntax-property #'val 'annotation #'ann #t)])) (annotate 4) ; -> #f (annotate 1 6) ; -> 1 (annotate (annotate 4 2)) ; -> 2 -- 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.
[racket-users] composing unquote-rewriters in redex?
To get rid of racket expressions that have been embedded in metafunctions and reduction relations, you use `with-unquote-rewriter`, but you can currently only have one rewriter active at a time (as underneath it's a single parameter that holds a function). I've been writing a little library to make working with rewriters a little more friendly, I expose a rewriter stack that you can push and pop atomic and compound rewriters to. I've been thinking about how best to add support for unquote rewriters, but I'm stumped. One possibility that occurred to me was to have pushing an unquote rewriter procedure RW onto the stack just set the current unquote rewriter to a function that calls RW on the lw in question, and if RW produces an lw where the unq? field is true, then that is the result, otherwise use the previous unquote rewriter (thus rewriters that don't want to make a change pass responsibility up the stack). Other than the fact that this could get rather slow when the unquote-rewriter stack gets really deep, redex currently doesn't publicly export the current-unquote-rewriter parameter. Would it be possible to make that change? In the meantime I suppose I shall make my own parameter for keeping track of unquote-rewriters, though this has the disadvantage of not knowing anything about unquote-rewriters set with the with-unquote-rewriter macro. Another thought that would require more effort, why is there only ever a single unquote-rewriter at a time? compound-rewriters and atomic-rewriters both have a table, allowing multiple rewriters to be layered on top of each other? Anyway thanks, Matias Eyzagurre. -- 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.
[racket] pfds package conflict in racket 6.0
Hi, When I try to install the pfds package under racket 6.0, it says that it depends on typed-racket-compatibility, which it then says conflicts with typed-racket-lib. I’m guessing that the dependency needs to be updated? Thanks, Matias Eyzaguirre Racket Users list: http://lists.racket-lang.org/users
[racket] typesetting scribble/lp files individually
Hi all, I’ve been using scribble/lp for a little while, but it’s starting to get annoying that using it seems to require a second module to lp-include the scribble/lp module in order to be able to typeset/render it. It doesn’t look like there’s a way to do it, but I thought I’d ask. If there isn’t, would it be possible to add one? Even just having the pdf and html buttons in the DrRacket toolbar be usable with scribble/lp files would greatly reduce the tedium of switching back and forth between my program and a file that just contains a call to lp-include. Thanks, Matias Eyzaguirre Racket Users list: http://lists.racket-lang.org/users
[racket] Scribble with color-property and background-color-property
Hi all,
When I use color-property and background-color-property in scribble they work
as expected when I generate HTML output, but do not seem to have any effect
when I generate PDF output. Do they not work with the LaTeX renderer?
On the other hand, I’m not very familiar with scribble so It’s easily possible
I’m doing something wrong. My document looks like this:
#lang scribble/base
@(require (only-in scribble/core style color-property
background-color-property))
@(define ugly-style
(style 'ugly (list (color-property "red")
(background-color-property "blue"
@para[#:style ugly-style]{Hello, this is incredibly ugly text}
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[racket] syntax-case + boxes and hash literals
#lang scribble/lp I've been to write some macros but I've run into some rather annoying limitations of syntax-case. They all involve deconstructing/pattern-matching literal boxes and literal hash tables. As per the pattern grammer in the reference guide, I can use syntax case to match against vectors, lists, and prefab structures, like so: @chunk[<*> (syntax-case #'(1 #(b 2) #s(silly 3)) () [(a #(_ b) #s(silly c)) #'(a b c)])] However I cannot do the same with boxes or hash literal. I can match syntax that contains boxes, like so: @chunk[<*> (syntax-case #'(1 #&2 #(3)) () [(a b #(c)) #'(a b c)])] But I cannot pattern match inside of the box itself. I would have expected that the following return a syntax object containing 1, 2, and 3 in a list. Instead it gives an error that says "?: bad syntax in: (1 #(b 2) #&3)" @chunk[<*> (syntax-case #'(1 #(b 2) #&3) () [(a #(_ b) #&c) #'(a b c)])] Why is this? It's my understanding that syntax-case is an older features, and so perhaps it just wasn't updated when newer constructs arrived. Was this an intentional decision, or did it slip through? If it did, could I ask that it be added to the TODO list? Thanks, Matias Eyzaguirre Racket Users list: http://lists.racket-lang.org/users
[racket] plist limitations
The plist library in xml/plist will only allow for plists whose root element is a dictionary, and complains bitterly when it is anything else. However many plists have an array in their root. I'm unsure what the reasoning for this is, but I think it could be considered a bug; however I'm unsure what the process is for reporting bugs in racket. signature.asc Description: Message signed with OpenPGP using GPGMail Racket Users list: http://lists.racket-lang.org/users
