It's just a graph implementation in Common Lisp. It may eventually become more than that.
The package is nicknamed jgraph.
Get behind your repl and execute this gem -
(load "compile.lisp")
Having quicklisp installed will help make sure this doesn't fail.
(load "test.lisp")
We use lisp-unit for our test suite. Coverage is currently dismal. But then again, so are the features.
There are currently two implementations of the graph - one using an object oriented approach, and one using Lisp's builtin association-list type. The association-list implementation is deprecated - CLOS contributes method overloading and information-hiding structures that are nice enough it wouldn't make sense to go without.