[racket] Problem with get-time-stamp

Hello, is there a documented problem with (send e get-time-stamp) ? After upgrading from 5.1.2 to 5.2, suddenly all mouse events have a time-stamp of 0.

Thanks

Mathieu Paradis

> Date: Wed, 1 Feb 2012 10:11:55 -0700
> From: ryan at cs.utah.edu
> To: rac at ruediger-asche.de
> CC: users at racket-lang.org
> Subject: Re: [racket] macros in local namespaces?...
> 
> On 02/01/2012 09:45 AM, Rüdiger Asche wrote:
> > Hi there,
> >
> > I'm trying to get a grip on macros. Here is a very simple Racket expression  (1):
> >
> > (letrec [(a 2)
> >          (b 3)
> >          (afn (lambda (x) (+ x a)))
> >          (bfn (lambda (x) (+ x b)))]
> >    (afn (bfn 2)))
> >
> > Now I need a syntactic abstraction for afn and bfn. The following will do in first approximation (2):
> >
> > (define-syntax-rule (absfn varname) (lambda (x) (+ x varname)))
> >
> > (letrec [(a 2)
> >          (b 3)
> >          (afn (absfn a))
> >          (bfn (absfn b))]
> >    (afn (bfn 2)))
> >
> >
> > However, it will fail due to scoping rules in the following example (3):
> >
> > (define-syntax-rule (absfn varname) (lambda (x) (+ (+ x localc) varname)))
> >
> > (letrec [(a 2)
> >          (b 3)
> >          (localc 4)
> >          (afn (absfn a))
> >          (bfn (absfn b))]
> >    (afn (bfn 2)))
> >
> > In other words, my syntactic extension absfn needs to be embedded in the namespace of the sorrounding expression (or as a "dumb" macro which simply does lexical replacement without considering scoping, but needless to say such a macro would be unhygienic).
> > I suspect that letrec-syntax was meant for that purpose, but I can't figure out how the parameters to define-syntax-rule would translate to those of letrec-syntax.
> >
> > Does anyone have sample code for how to get (3) above to work?
> >
> > Thanks!
> 
> The easiest way is to use internal definitions instead:
> 
> (let ()
>    (define a 2)
>    (define b 3)
>    (define localc 4)
>    (define-syntax-rule (absfn varname)
>      (lambda (x) (+ (+ x localc) varname)))
>    (define afn (absfn a))
>    (define bfn (absfn b))
>    (afn (bfn 2)))
> 
> Another way is to use letrec-syntaxes+values, as Matthias answered.
> 
> Ryan
> ____________________
>   Racket Users list:
>   http://lists.racket-lang.org/users
 		 	   		  
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.racket-lang.org/users/archive/attachments/20120202/604bd3e8/attachment.html>