Clojure is the best all-purpose programming language that I have yet to encounter in my software development career. When I first began learning it, I found myself thrilled and satisfied in ways that I can only recall experiencing once beforeùwhen I received my first computer, and entered those first few commands and watched in delight as it responded with precision to my instructions. Over the years, of course, much of the charm of programming wore off. The excitement of imposing my will on a complex machine gradually became lost as I repeatedly slogged through the same exercises and patterns, overcoming with difficulty the inherent complexities of ever-larger systems. But with Clojure, I noticed a curious shift. I began, once more, to enjoy the act of programming. Not just the act of creation and planning, which I"ve always liked, but even implementing low-level, "everyday" routines. Programming in Clojure is like removing a restrictive suitùonce more, you"ll feel like you are actually in control, expressing yourself to the program directly rather than through layers of vaguely necessary indirection. You will be impressed and pleased with Clojure"s expressiveness, allowing scope for creativity and original abstractions. Instead of programs becoming more complex and difficult to understand as they grow, Clojure programs become simpler and more expressive. More than that, Clojure will encourage you to try things that are simply too complicated to do regularly in other languages: concurrency, immutability, and lazy data structures. Plus since it runs on the JVM, you can use the same platform, libraries, and tools that you are comfortable with. I hope that this book opens the same doors for you as it did for me, and shows Clojure to be the fun, expressive, and mature language that I have found it to be. Sincerely, Luke VanderHart