# Parsing package names and versions.
guix build -n time # PASS
-guix build -n time-1.7 # PASS, version found
-if guix build -n time-3.2; # FAIL, version not found
+guix build -n time@1.7 # PASS, version found
+if guix build -n time@3.2; # FAIL, version not found
then false; else true; fi
if guix build -n something-that-will-never-exist; # FAIL
then false; else true; fi