Book Image

Clojure for Java Developers

Book Image

Clojure for Java Developers

Overview of this book

We have reached a point where machines are not getting much faster, software projects need to be delivered quickly, and high quality in software is more demanding as ever. We need to explore new ways of writing software that helps achieve those goals. Clojure offers a new possibility of writing high quality, multi-core software faster than ever, without having to leave your current platform. Clojure for Java developers aims at unleashing the true potential of the Clojure language to use it in your projects. The book begins with the installation and setup of the Clojure environment before moving on to explore the language in-depth. Get acquainted with its various features such as functional programming, concurrency, etc. with the help of example projects. Additionally, you will also, learn how the tooling works, and how it interacts with the Java environment. By the end of this book, you will have a firm grip on Clojure and its features, and use them effectively to write more robust programs.
Table of Contents (14 chapters)
Clojure for Java Developers
Credits
About the Author
About the Reviewer
www.PacktPub.com
Preface
Index

Atoms


We have now seen how promises, futures, and transactions work in Clojure. We'll now see atoms.

Even though STM is very useful and powerful you'll see that in practice it is not very commonly used.

Atoms are one of Clojure's workhorses, when it comes to concurrent programming.

You can think of atoms as transactions that modify one single value. You might be thinking, what good is that? Imagine you had lots of events that you want to store in a single vector. If you are used to Java, you probably know that using a java.util.ArrayList package is bound to have problems; since, you are almost surely going to lose data.

In that case, you probably want to use a class from the java.util.concurrent package, how can you guarantee that you'll have no data loss in Clojure?

It's easy, atoms come to the rescue! Let's try this piece of code:

(clojure.core/use 'co.paralleluniverse.pulsar.core)
(def events (atom []))
(defn log-events [count event-id]
  (dotimes [_ count]
    (swap! events conj event-id)...