Lisp has an ecosystem all its own that is well outside of the box. As a result, few package managers have many packages for it (Debian has more than usual and is still missing a great many common packages). Of course, intrepid Lispers are not put off by this at all and create their own system definition systems. The most famous of these being, of course, asdf and mk-systems. Asdf is only half of what apt is for Debian. It defines sytems and dependencies, but it has no way to automatically grab and install any of these systems. At some point, asdf-install was created. It was an attempt to supply the missing half of apt for the Lisp universe. The only problem is that it doesn't work all that well. (Note: Mudballs is an attempt to both round out asdf into a full apt-like system with both system definition and administration; as a young project, it will be interesting to see what happens).

In the final analysis, what happens for most people (or me, at least) is that they find the libraries they need, download them to some specified destination and add the resulting directory to the asdf:*central-registry* in the startup lisp code for their interpreter so that a quick

(asdf:operate 'asdf:load-op 'foo)

Loads the system "foo". After delving into a bit of Lisp code, I quickly compiled a huge initialization file with many lines pushing each specific path onto the registry. A couple of days ago, I threw it all out and replaced it with a handful of lines that adds all of the directories beneath some predetermined directory to the registry. Ladies and Gentlemen, for your viewing pleasure, here is that code:

(require 'asdf)

(push #P"/home//lisp/cl-fad-0.6.2/" asdf:*central-registry*)
(asdf:oos 'asdf:load-op 'cl-fad)
(mapcar #'(lambda (path) (if (cl-fad:directory-pathname-p path)
                           (push path asdf:*central-registry*)))
        (cl-fad:list-directory #P"/home//lisp/"))

To sum up, you replace with your real username (or the whole path) with your username. What I do, is keep a directory called "lisp" (creatively enough) and download all of my development libraries into that directory. This code makes it so that that is all I have to do to add a library. Enjoy!