Return a package matching SPEC. SPEC may be a package name, or a package name followed by an at-sign and a version number. If the version number is not present, return the preferred newest version.

Search the auxiliary FILE-NAME. Return #f if not found.

Fold PROC over the list of available packages. For each available package, PROC is called along these lines:

(PROC NAME VERSION RESULT #:outputs OUTPUTS #:location LOCATION …)

PROC can use #:allow-other-keys to ignore the bits it's not interested in. When a package cache is available, this procedure does not actually load any package module.

Call (PROC PACKAGE RESULT) for each available package defined in one of MODULES that matches SELECT?, using INIT as the initial value of RESULT. It is guaranteed to never traverse the same package twice.

Return the list of packages with the given NAME. If VERSION is not #f, then only return packages whose version is prefixed by VERSION, sorted in decreasing version order.

Return true if the pre-computed package cache is authoritative. It is not authoritative when entries have been added via GUIX_PACKAGE_PATH or '-L' flags.

Return a list of version/location pairs corresponding to each package matching NAME and VERSION.

Generate under DIRECTORY a cache of all the available packages.

The primary purpose of the cache is to speed up package lookup by name such that we don't have to traverse and load all the package modules, thereby also reducing the memory footprint.