CLAI and PSL are both Lisp-based artificial intelligence frameworks, with CLAI focusing on expert systems and PSL providing a portable implementation of the Common Lisp programming language.

Another good Lisp book that's a tough read but well worth it is Peter Norvig's <I>Paradigms of Artificial Intelligence Programming: Case Studies in Common Lisp</I>.

• Common Lisp programming, including • Symbols, lists, strings, arrays, and other built-in data structures • Structures and the Common Lisp Object System (CLOS) • Functions and macros • Recursion and ...