Programming in Emacs Lisp. Mark Watsons opinions on Java, Ruby, Lisp, An Introduction to Common Lisp Macro. Macros in Lisp provide a very powerful and flexible method of extending Lisp syntax. They are much, much more powerful than #define macros in C: Lisp macros are a full-fledged code-generation system, while C #define macros are simple string substitutions.
Although extremely powerful and useful, macros are also significantly harder to design and debug than normal Lisp functions, and are normally considered a topic for the advanced Lisp developer. Lisp functions take Lisp values as input and return Lisp values. They are executed at run-time. Lisp macros take Lisp code as input, and return Lisp code. Lisp Primer.