Excerpts from Roberto's message on Aug 5, 2009 about 11 AM:
the problem you describe seems more related to SWI-Prolog than to the PPL. Anyway, I have tried to reproduce your observations on a machine where we have Debian, but it is the Etch version. Moreover, here is what I obtain trying to install SWI-Prolog:
debian:~# apt-get install swi-prolog Reading package lists... Building dependency tree... E: Package swi-prolog has no installation candidate Package swi-prolog is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source
Umm. I am trying with Debian Sid, which is the unstable version of Debian. It contains (somewhat) up to date packages. Among them, SWI Prolog.
Any suggestion? Which version of SWI-Prolog are you using? Did you install it from sources?
I am using SWI Prolog 5.6.59, installed using the swi-prolog package of Debian Sid.
It can also be reproduced with the latest Ubuntu (9.04, Jaunty). If you want to try, I can provide instructions to compile the package in another message (it requires to modify the packaging scripts to add the SWI Prolog support, which is disabled by default).
In any case, if this is the first time you see this, it is likely that it is related to SWI Prolog, or to the packaging scripts, or both.
I have seen similar errors in the Debian bug tracking system, with other packages depending on SWI Prolog. However, the solution was not posted. I thought it could be related to the Prolog sources, that's why I asked here. I am going to contact the Debian maintainers of those packages, and of PPL, maybe they know how to fix it.
In the end, this means that I am going to ask for PPL support to be added to the official PPL Debian packages. I will post to this list if there is any news about this.
Actually, I have managed to compile the packages, just skipping the tests, but I don't like this solution, because after all tests are there for something :-). If you are curious or you want to try the packages out, I can provide info about the repositories where I have the packages (only for Debian Sid and Ubuntu Jaunty).
Thanks for the feedback.
Israel