An Introduction to Programming in Emacs Lisp

This tutorial an elementary introduction to teach non-programmers how to customize their work environment; it can also be used as an introduction to programming basics. It includes numerous exercises and sample programs; the author also walks you through the actual source code of several GNU Emacs commands. A handy reference appendix is included.
Emacs Lisp is a simple, complete, and powerful programming language. It is the building block of GNU Emacs, which is an integrated development environment with special features for scanning and parsing text as well as for handling multiple files, buffers, displays, windows, and sub-processors.
This book will show you:
* how to set variables and write function definitions
* How to use "if" and "let"
* How to write "while" loops and recursive loops
* how to search for a word or expression
* how to customize GNU Emacs for yourself, even when it is shared on a network.
* how to debug programs
* and much more.
This revised second edition covers new features included in GNU Emacs version 21, while remaining compatible with earlier versions.