P. Seibel
Publisher: Apress
Cited by:
Practical Common Lisp by Peter Seibel. It's equally difficult to choose a programming book, because many, many books have shaped my life. I've chosen Practical Common Lisp, because as far as I can remember it's the first book I got when I was exploring "alternative" programming languages - languages other than things like PHP, Java, C# that I was probably writing at the time. Lisp was eye-opening to me for being radically different in almost every way. Code as data, the syntax was alien, the ideas of higher-order functions, but even the way you interacted with tools such as via a REPL - all of these have quite literally changed the way I write code to this very day.
-- Oliver Charles