Stuart Halloway

Clojure is a dynamic language for the Java Virtual Machine, with a compelling combination of features:

Clojure is elegant. Clojure's clean, careful design lets you write programs that get right to the essence of a problem, without a lot of clutter and ceremony.

Clojure is Lisp reloaded. Clojure has the power inherent in Lisp, but is not constrained by the history of Lisp.

Clojure is a functional language. Data structures are immutable, and functions tend to be side-effect free. This makes it easier to write correct programs, and to compose large programs from smaller ones.

Clojure is concurrent. Rather than error-prone locking, Clojure provides software transactional memory.

Clojure embraces Java. Calling from Clojure to Java is direct, and goes through no translation layer.

Clojure is fast. Wherever you need it, you can get the exact same performance that you could get from hand-written Java code.

Many other languages offer some of these features, but the combination of them all makes Clojure sparkle. Programming Clojure shows you why these features are so important, and how you can use Clojure to build powerful programs quickly.

Many Java developers are now looking at Ruby, and the Ruby on Rails web framework. If you are one of them, this book is your guide. Written by experienced developers who love both Java and Ruby, this book will show you, via detailed comparisons and commentary, how to translate your hard-earned Java knowledge and skills into the world of Ruby and Rails.

If you are a Java programmer, you shouldn't have to start at the very beginning! You already have deep experience with the design issues that inspired Rails, and can use this background to quickly learn Ruby and Rails. But Ruby looks a lot different from Java, and some of those differences support powerful abstractions that Java lacks. We'll be your guides to this new, but not strange, territory.

In each chapter, we build a series of parallel examples to demonstrate some facet of web development. Because the Rails examples sit next to Java examples, you can start this book in the middle, or anywhere else you want. You can use the Java version of the code, plus the analysis, to quickly grok what the Rails version is doing. We have carefully cross-referenced and indexed the book to facilitate jumping around as you need to.

Thanks to your background in Java, this one short book can cover a half-dozen books' worth of ideas: