Another free Lisp book, one that focuses on macros -- and is quite readable -- is YC-founder Paul Graham's "On Lisp". There's a download page [0] (for the book

Another free Lisp book, one that focuses on macros -- and is quite readable -- is YC-founder Paul Graham's "On Lisp". There's a download page [0] (for the book and code) at paulgraham.com as well as the following on a description page [1]: On Lisp is a comprehensive study of advanced Lisp techniques, with bottom-up programming as the unifying theme. It gives the first complete description of macros and macro applications. The book also covers important subjects related to bottom-up programming, including functional programming, rapid prototyping, interactive development, and embedded languages. The final chapter takes a deeper look at object-oriented programming than previous Lisp books, showing the step-by-step construction of a working model of the Common Lisp Object System (CLOS). As well as an indispensable reference, On Lisp is a source of software. Its examples form a library of functions and macros that readers will be able to use in their own Lisp programs. [0] http://www.paulgraham.com/onlisptext.html http://www.paulgraham.com/onlisptext.html [1] http://www.paulgraham.com/onlisp.html http://www.paulgraham.com/onlisp.html