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Warnings before you start with guile-iii

Keep in mind that libguile is rapidly evolving. The -iii snapshot had changed so much since the -ii snapshot that it took a lot of work and some email from Tom Lord to merge the gnudl software with the new guile.

In this tutorial, all examples work with guile-iii, but my opinion is that the programmer interface to libguile has been spoiled in guile-iii. I am encouraging Tom to clean it up somewhat, and this tutorial will be re-written to reflect future (maybe cleaner) snapshots of guile.

A few things need to be done to the guile-iii snapshot to make it work well; here are some of them, though I'm sure I'm missing others:

• The macro for gscm_vset() in `gscm.h' is wrong. It reads:

  #define gscm_vset(V, I, VAL)    scm_vector_set ((V), SCM_MAKINUM(I), (VAL))
  

  but it should read

  #define gscm_vset(V, I, VAL)    scm_vector_set_x ((V), SCM_MAKINUM(I), (VAL))
  

  You can just correct it in the `gscm.h' file.
• The file scmconfig.h needs to be copied to `/packages/include/guile/' manually; the software "make install" procedure does not do that for some reason.
• On SGIs you need to install recent versions of flex and bison; otherwise you might have trouble compiling.
• The make clean and make distclean are not to be trusted. If you make some change in the configuration of guile, or if you install flex, you cannot just do a make distclean; ./configure --prefix=whatever. I recommend that if you recompile with different circumstances, you re-extract the guile-iii.tar.gz archive.
• Until you are more familiar with guile you might want to only install the guile package, and not the tcl/tk and mesaglut plugins. I don't think they are really documented anyway... :-)
• I still find the approach to locating scheme library files a mystery. I install them in `/packages/lib/scm' for the SCM interpreter, and then I set my SCHEME_LIBRARY_PATH variable to be `/packages/lib/scm/' (note the trailing / (slash) character: it is necessary). But then Guile installs some things in /packages/lib/gls, but not enough things. And then if you install Aubrey Jaffer's most excellent slib (a portable scheme library with tons of goodies (see see section Useful references)), in `/packages/lib/slib', then how do you also have that searched? The SCHEME_LIBRARY_PATH variable is not colon-separated... So you have to learn to live with this mess, until Tom and Aubrey explain how we should do things in this department.
• There is a file `debug.scm' that comes with the slib library; this should be copied into the directory pointed to by SCHEME_LIBRARY_PATH, if not the print procedure in scheme will not work.

And in general, if you have trouble compiling, take a look at the hypermail archive of the gel@cygnus.com mailing list (URL http://www.cygnus.com/ml/gel/).

But even with these warnings, I still think that guile is the answer to a lot of questions in developing large software packages, and I strongly recommend you go ahead and use it.

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