Clojure: Getting Started

Introduction
Often people will ask me how to get started in Clojure. Most often they have a Java background, but sometimes they are coming from C++, Python, or some other popular language. Either way, I rehash the same story and spent a bunch of time finding and consolidating the same links as the last time someone asked me this question.

This post is meant to be my simple, consolidated answer to "How do I get started with Clojure?"

Here's how...

Pick a Project
Before you do anything else, you really need to pick some simple project you will do in Clojure. In my experience, attempting to learn something without some concurrent hands-on experience isn't particularly effective. My first non-trivial (i.e. (prn "Hello World)) application was an implementation of the board game Cartagena that I talked about at Clojure/conj. You can watch it right here:

I suggest an application that has some state, whether it be a desktop application or single page web app (using ClojureScript). That way you can use atoms and understand how Clojure separates the concerns of state (atoms, agents, or refs), value (data), and transition (functions). I think board games make excellent projects, but then again I really like board games. You could do just about anything.

Watch & Read
Here are a few links I recommend to everyone, not in any particular order. They are all excellent.

• Clojure for the Brave and True: Daniel Higginbotham's truly awesome book/online learning series on learning Clojure from the ground up. Buy it here. This is my #1 recommended getting started resource.
• Clojure Evaluation: The single most important documentation page on Clojure in the entire universe. Once you understand this page you pretty much know the entire language (not the APIs). Yes, Clojure is this simple.
• Clojure - Functional Programming for the JVM: Mark Volkmann's extremely direct and to the point single web page description of Clojure.
• Rich Hickey's Greatest Hits: Most of these are more philosophical than tutorial in nature, but they give you great insights into the genius behind Clojure. Key concepts such as value, state, identity, etc. are described in these videos. My favorites:
• Are We There Yet?
• Simple Made Easy
• The Value of Values

In Conclusion

Hopefully the above tips and links will give you a little help if you are considering Clojure and want to know where to start. Either way, I'll have something to point to next time someone asks me.