OK, I did some research. The issue is as follows:
- Virtually all guile packages declare guile an input, but not a
propgated input. This seems to make Guile available in the
environment, but without the Guile environment paths defined.
- Guile-DBI on the other hand seems to declare guile a propagated
input. This causes the environment paths to be set.
- Similarly, when you install in your profile:
+ installing guile too will encourage you to set up the environment
path.
+ installing only the library will not.
+ installing only guile will not do this either (see the example in
the manual, at
https://www.gnu.org/software/guix/manual/en/html_node/Invoking-guix-package.html#index-search-paths
- When you install, either in environment, or in profile, both guile and
a guile-library, the env variables are set/reported correctly.
This looks like it is intended behaviour.
Please test and let me know if this resolves the issue for you!