Ya, the language itself is not very well documented. But it's mostly Common LISP like, though a LISP-1 like Scheme, which is the biggest deviation from Common LISP.
You can take a look at core.lisp and html.lisp in the lisp/ directory, as well as the test cases for example code in test/.
You can take a look at core.lisp and html.lisp in the lisp/ directory, as well as the test cases for example code in test/.