TFM (for TeX Font Metric) is the standard font description format used by TeX. The TFM library parses and decodes TeX Font Metric and similar formats into an abstract data structure, providing easy access to the corresponding font information in Common Lisp.
In addition to regular TFM data, the library also supports level 0 Omega (OFM) fonts.
In your favorite Lisp REPL, type something like this:
(asdf:load-system :net.didierverna.tfm)
(net.didierverna.tfm:nickname-package)
(defvar *cmr10* (tfm:load-font #p"/path/to/cmr10.tfm"))
You will end up with a font object, containing the decoded font information,
and stored in an easily accessible way. Inspect the object in question to
familiarize yourself with its contents.
TFM comes with both a user manual and a reference manual. Please see the projet's homepage for more information.