Functional Programming is back! After 2-3 decades of Object Oriented Programming which made languages like Lisp seem like a dinosaur, the software community has turned its focus back on FP. And with good reason! OOP has fallen short of the demands of concurrent programming leading to convoluted code that only a few experts can read and write. New FP languages today like Scala or Clojure address this issue by providing a robust language that can run on the good old reliable JVM. That way you don't need a huge change in your infrastructure - just add a few jars and you are ready to dive in. This book will teach you how.
If you have been wondering about Software Transactional Memory, The Actor Model, MapReduce, and other buzz words that have been going around lately, its time to pick this book. The author does a fine job of explaining what FP is, what it aims to solve, when to use it, and how to get started with it. The author explains very well the differences between imperative (OOP) and declarative (FP) programming.
This book is a brief introductory book that scratches the FP arena. By no means there is any depth provided. Developers looking for developing expertise in a particular FP language have to look elsewhere but might benefit from reading this book to get a good overview.