[Snow-users-list] snowman-app port problems in Guile

Ludovic Courtès ludo at gnu.org
Tue Apr 15 03:17:16 EDT 2008

Hi Marc,

Marc Feeley <feeley at iro.umontreal.ca> writes:

> The escapes are generated by the snowfort server.  The server, a  
> Scheme program, serializes the list of packages using "write" and the  
> snowman client will deserialize it using "read".  In this case the  
> server is running on Gambit and the client is running on Guile.   
> Gambit's syntax for strings is compatible with C and the \ooo octal  
> notation is how non-ASCII LATIN-1 characters are written.  Although  
> this syntax is not universal among Scheme implementations, it is a  
> fairly common extension to the standard Scheme syntax (supported by  
> Bigloo, Chez, Gambit, Kawa, MzScheme, Scsh and probably others).   
> Unfortunately Guile does not implement this extension.  Note that the  
> snowfort server could be run using some other Scheme system, but that  
> does not solve the problem because the issue is the incompatibility of  
> the server's write and the client's read.  That's what standards are  
> meant to solve.

Thanks for the explanation.

> So what to do?  There is no standard way in Scheme to write non-ASCII  
> characters (in fact one could say that no character can be portably  
> written since Scheme does not define the character set!).  Specific  
> serializer/deserializer algorithms other than write/read could be  
> implemented but that would be a real pain and it would make I/O really  
> slow on interpreted systems.
> The pragmatic solution is to avoid non-ASCII characters in Scheme  
> code, and Snow packages in particular.

That's one solution, but as someone with an accent in his name, I don't
like it so much.  ;-)

I can think of two solutions:

  1. provide a `read' replacement for implementations that are known to
     not support this syntax (but as you say, this may result in much
     slower I/O, especially on Guile);

  2. implement said syntax in Guile.

The latter is doable (and makes sense if everyone else does it), but the
former would allow Snow to run with current versions of Guile.


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