[plt-scheme] . nitpick .

Ryan, Robby, Anton,
Thanks for the corrections and explanations.
Jos Koot

----- Original Message ----- 
From: "Ryan Culpepper" <ryanc at ccs.neu.edu>
To: "Jos Koot" <jos.koot at telefonica.net>
Cc: "Grant Rettke" <grettke at acm.org>; "PLT Scheme" 
<plt-scheme at list.cs.brown.edu>; "Anton van Straaten" <anton at appsolutions.com>
Sent: Sunday, June 10, 2007 11:20 PM
Subject: Re: [plt-scheme] . nitpick .


> On Sun, 2007-06-10 at 19:07 +0200, Jos Koot wrote:
>> For the toplevel:
>>
>> (require (lib "r5rs" "lang"))
>> (current-namespace (module->namespace '(lib "r5rs" "lang")))
>
> Careful: that's not the right way to get a namespace with just the
> bindings from some module X. Instead, that gets you everything bound
> *inside* module X. It gives you access to the module's unexported
> bindings---including everything that it imports. It bypasses contracts
> placed on exports with 'provide/contract'. It doesn't do renaming or
> prefixing of exports, either. Unfortunately, on this particular module,
> it happens not to make a difference, so your code worked.
>
> 'module->namespace' is the right solution to only a very small set of
> problems. It's the most invasive thing one can do to a module.
> Programming environments and testing frameworks can get away with it,
> but ordinary programs, even those that deal with namespaces, shouldn't.
>
> Here's one way to get a namespace with only the bindings for a
> particular module "X":
>
>  ;; namespace-from-module : module-name -> namespace
>  ;; Constructs a namespace containing bindings for only the
>  ;; exports of the given module.
>  (define (namespace-from-module the-module)
>    (let ([orig-ns (current-namespace)])
>      (dynamic-require the-module #f)  ;; make sure module initialized
>      (parameterize ((current-namespace (make-namespace 'empty)))
>        (namespace-attach-module orig-ns the-module)
>        (namespace-require the-module)  ;; import the bindings
>        (current-namespace))))
>
> Then:
>
>  (namespace-from-module '(lib "r5rs.ss" "lang"))
>
> There are many variations on this code. If you want the consumer of the
> namespace to be able to set! the value bindings, use
> 'namespace-require/copy' to import the bindings instead. If you want to
> allow macro definitions, you'll need to use
> 'namespace-transformer-require' to put something in the transformer
> environment too. If you want a fresh instantiation of the module, then
> remove the call to 'dynamic-require' and only attach '(quote mzscheme)'
> instead of 'the-module'. And so on.
>
> Ryan
>
>>
>> Jos Koot
>>
>> ----- Original Message ----- 
>> From: "Grant Rettke" <grettke at acm.org>
>> To: "Jos Koot" <jos.koot at telefonica.net>
>> Cc: "Anton van Straaten" <anton at appsolutions.com>; "PLT Scheme"
>> <plt-scheme at list.cs.brown.edu>
>> Sent: Sunday, June 10, 2007 6:56 PM
>> Subject: Re: [plt-scheme] . nitpick .
>>
>>
>> > Does that do something like saying that only the r5rs functions will
>> > exist in the current name space?
>> >
>> > On 6/10/07, Jos Koot <jos.koot at telefonica.net> wrote:
>> >>
>> >> ----- Original Message -----
>> >> From: "Grant Rettke" <grettke at acm.org>
>> >> To: "Jos Koot" <jos.koot at telefonica.net>
>> >> Cc: "Anton van Straaten" <anton at appsolutions.com>; "PLT Scheme"
>> >> <plt-scheme at list.cs.brown.edu>
>> >> Sent: Sunday, June 10, 2007 6:25 PM
>> >> Subject: Re: [plt-scheme] . nitpick .
>> >>
>> >>
>> >> >I wonder why there isn't a r5rs module.
>> >>
>> >> But there is: (lib "r5rs" "lang")
>> >> Jos Koot
>> >>
>> >>
>> >> >
>> >> > On 6/10/07, Jos Koot <jos.koot at telefonica.net> wrote:
>> >> >> One could set (read-accept-dot #f) as default for language R5RS.
>> >> >> Adding (read-accept-dot #f) to .../collects/r5rs/lang.ss does the 
>> >> >> trick,
>> >> >> although another location may be more appropriate.
>> >> >> Jos koot
>> >> >>
>> >> >> ----- Original Message -----
>> >> >> From: "Anton van Straaten" <anton at appsolutions.com>
>> >> >> To: "PLT Scheme" <plt-scheme at list.cs.brown.edu>
>> >> >> Sent: Sunday, June 10, 2007 4:15 PM
>> >> >> Subject: [plt-scheme] . nitpick .
>> >> >>
>> >> >>
>> >> >> > Shouldn't the R5RS language level disallow the infix dot syntax?
>> >> >> >
>> >> >> > As seen in this message:
>> >> >> >
>> >> >> > http://groups.google.com/group/comp.lang.scheme/msg/40f19cb9863cf28d
>> >> >> >
>> >> >> > ...someone experimenting can get confused by the infix feature.  It
>> >> >> > would
>> >> >> > be
>> >> >> > helpful to be able to respond to that by saying "that's an 
>> >> >> > extension --
>> >> >> > use
>> >> >> > the R5RS language level if you want to experiment with standard 
>> >> >> > Scheme
>> >> >> > behavior".  But here, we can't say that.
>> >> >> >
>> >> >> > Anton
>> >> >> >
>> >> >> > _________________________________________________
>> >> >> >  For list-related administrative tasks:
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>> >> >> >
>> >> >>
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>> >> >
>> >>
>> >>
>> >
>>
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