You raise a valid concern, mlslk31. Here is my understanding of the current state of things with regard to updating to Guile 2.0.
To my knowledge, there are no packages in Slackware -current that would be broken by the upgrade. The SWIG
interface library did not support Guile 2.0 prior to version 2.0.10, but -current is now shipping SWIG 2.0.10
There are some SlackBuilds from slackbuilds.org that will be affected. The version of Xbindkeys (version 1.8.5)
specified by the Slackware 14 SlackBuild is already compliant with Guile 2.0 and thus should not present a problem.
The version of Ardour (version 2.8.14)
specified by the Slackware 14 SlackBuild
successfully builds and runs against Guile 2.0 but it is possible that there are a couple of scripts that still need updating. Any such bug would only mean the loss of that particular script's functionality, and the Ardour developers have been very diligent in addressing these issues.
There is no SlackBuild for the GNOME card game AisleRiot
but for those who wish to build their own package, Guile 2.0 may present a problem as the AisleRiot changelogs do not appear to mention any changes driven by Guile 2.0 support. This does not necessarily mean that Guile 2.0 is incompatible. The big change in Guile 2.0 that has been causing grief is that macros can no longer be used before they have been defined (Guile 1.8 was forgiving of this). If no such undefined macros are used then backwards compatibility with Guile 2.0 should not be a problem. Guile is used by AisleRiot only for generating the HELP system; not to trivialize this, however, the games should still work without help being available.
There is also no SlackBuild for the Dr GEO
geometry program, which has Guile 1.8 as a dependency. I am completely unfamiliar with this program, and have no idea whether it would be impacted by an upgrade of Guile to 2.0.
The SlackBuild for GNUcash
is currently at version 2.4.11, which will not
build against Guile 2.0. Support for Guile 2.0 is available in GNUcash version 2.5.2 of the development branch. I imagine SB.o would prefer to stay with the stable 2.4 branch but I believe there have been exceptions made in the past.
One of the more problematic programs would be the Lilypond
music notation software. Its SlackBuild for SW 14.0
specifies version 2.16.1 and, as was the case for GNUcash, this would need to be bumped up to the 2.17 development branch to work with Guile 2.0. The Guile-driven changes in the 2.17 branch are too extensive to expect that they'd be backported to the 2.16 branch.
Lilypond also presents a problem in that the Slackware 'texi2html' utility (included in the Tetex 3.0
package would need to be upgraded from version 1.76 to version 1.82 in order for Lilypond 2.17.20 to work with Guile 2.0. Other than the Guile package itself, Tetex is the only other package in Slackware proper that should need upgrading.
That is my best assessment of the impact upon Slackware of upgrading to Guile 2.0. If I have made a mistake or have missed anything, please let me know.