Say ‘geometry’ needs your ‘vectors’ library. Add:
depends-on ("vectors")
to the definition. Now ‘(alpm-load-system "geometry" nil)’ first locates ‘vectors.alpm’ (in the registered directories), loads the ‘vectors’ system completely, then loads ‘geometry’’s own files. Dependencies are transitive and loaded exactly once; circular system dependencies are detected and reported as an error with the cycle spelled out.
File-level ‘depends-on’ can only name files of the same system; if a file needs another system, put that system in the system-level ‘depends-on’.