Re: [racket-users] namespace-anchor->namespace and eval

[Laurent]

Ah so that was actually a bug then :) Thanks for fix!

On Thu, Oct 5, 2017 at 5:47 PM, Matthew Flatt  wrote:

> I've pushed a repair for this problem. It's a bug in the current
> expander that could be triggered by a just-right combination of
> `syntax-local-lift-expression` (as used by `new`) and `expand` (as used
> by errortrace, which is used by DrRacket).
>
> At Sun, 1 Oct 2017 16:05:16 +0100, Laurent wrote:
> > Hi,
> >
> > Does anyone know a good explanation as to why the following code works
> > depending on whether the apparently-useless line is commented out?
> >
> > #lang racket
> >
> > #;(new object%) ; uncommenting this raises an error
> >
> > (define-namespace-anchor nsa)
> > (define ns (namespace-anchor->namespace nsa))
> > (eval '(new object%) ns)
> >
> > The error is:
> > lifted.0.0: undefined;
> >  cannot reference an identifier before its definition
> > with syntax location on the eval line
> >
> > Thanks!
> >
> > --
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Re: [racket-users] namespace-anchor->namespace and eval

[Matthew Flatt]

I've pushed a repair for this problem. It's a bug in the current
expander that could be triggered by a just-right combination of
`syntax-local-lift-expression` (as used by `new`) and `expand` (as used
by errortrace, which is used by DrRacket).

At Sun, 1 Oct 2017 16:05:16 +0100, Laurent wrote:
> Hi,
> 
> Does anyone know a good explanation as to why the following code works
> depending on whether the apparently-useless line is commented out?
> 
> #lang racket
> 
> #;(new object%) ; uncommenting this raises an error
> 
> (define-namespace-anchor nsa)
> (define ns (namespace-anchor->namespace nsa))
> (eval '(new object%) ns)
> 
> The error is:
> lifted.0.0: undefined;
>  cannot reference an identifier before its definition
> with syntax location on the eval line
> 
> Thanks!
> 
> -- 
> You received this message because you are subscribed to the Google Groups 
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> To unsubscribe from this group and stop receiving emails from it, send an 
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Re: [racket-users] namespace-anchor->namespace and eval

[Philip McGrath]

I have no explanation, but I can get a longer version of the error message.
If you change the definitions to:

#lang racket

(new object%)

(define-namespace-anchor nsa)
(define ns (namespace-anchor->namespace nsa))

And then evaluate at the REPL:

> (eval '(new object%) ns)

You get this error message:

../../Applications/Racket
v6.10/collects/racket/private/class-internal.rkt:3313:7: lifted.0.0:
undefined;
 cannot reference an identifier before its definition

-Philip

On Sun, Oct 1, 2017 at 10:05 AM, Laurent  wrote:

> Hi,
>
> Does anyone know a good explanation as to why the following code works
> depending on whether the apparently-useless line is commented out?
>
> #lang racket
>
> #;(new object%) ; uncommenting this raises an error
>
> (define-namespace-anchor nsa)
> (define ns (namespace-anchor->namespace nsa))
> (eval '(new object%) ns)
>
> The error is:
> lifted.0.0: undefined;
>  cannot reference an identifier before its definition
> with syntax location on the eval line
>
> Thanks!
>
>
>
> --
> 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.
>

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