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

Matthew Martin matt.a.martin at gmail.com
Mon Apr 14 22:15:53 EDT 2008

Guile supports SRFI-14, as do most of the other "big" implementations.
Gambit isn't listed at http://srfi.schemers.org/srfi-implementers.html
at all though. Might it help?

"This library is designed to be portable across implementations that
use different character types and representations, especially ASCII,
Latin-1 and Unicode."

On Mon, Apr 14, 2008 at 8:12 PM, Marc Feeley <feeley at iro.umontreal.ca> wrote:
>  On 14-Apr-08, at 11:36 AM, Ludovic Courtès wrote:
>  >  (author: "Danny Dub\351 <Danny.Dube at ift.ulaval.ca>")
>  >  (author: "Adrien Pi\303\251rard <pierarda at iro.umontreal.ca")
>  >
>  > It's these escape sequences that make Guile's reader unhappy.
>  >
>  > However, I don't understand where they come from.  When I download the
>  > snowballs that contain these strings "by hand" from the Snow
>  > website, I
>  > can see that they do not contain the escape sequences, but rather a
>  > UTF-8 or Latin-1 representation of these author names.  So I suppose
>  > the
>  > escape sequences get added somehow as the strings are sent over HTTP.
>  >
>  > Can someone shed some light on this?
>  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.
>  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.
>  Marc
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