Macsyma/Maxima is a computer algebra system written in Lisp, full 20 years older than Mathematica. It implements similar evaluation capabilities. The book Para

Macsyma/Maxima is a computer algebra system written in Lisp, full 20 years older than Mathematica. It implements similar evaluation capabilities. The book Paradigms of AI Programming by Peter Norvig shows how to implement these evaluation strategies in efficient Common Lisp.