Code Play a software blog by tim benke

Taming the Parentheses - Get Started With Clojure


The first big difference of Clojure to C-style languages like Java and Javascript are the parentheses. To some they seem overly abundant, although the style is not that different.

println("hello world")

is valid Python 3 while Clojure has

(println "hello world")

Clojure now goes one step further and applies the same principle to almost anything like e.g. function declaration:

(defn fun [param]

(watch talk)

To get a better sense if Clojure is for you, I suggest watching the excellent talk Clojure, made simple by the language creator Rich Hickey.

At my company I’ve held a Clojure talk recently too and tried to give an overview of the language and present its applications in web development. Of course without a video you miss out on the demos but it might be worth to skip through quickly anyway: Clojure - The Average Joe’s Lisp.

My goal was to show that Clojure is far from the stereotype of an academic esoteric language and can be learned easily to elegantly solve real-world problems.

Some other people have also taken a stab at this. The clean-code guru Robert Martin aka Uncle Bob have written about how they like Clojure: Clojure Is the New C, Why Clojure?


If you want to dive right in and write code, try the online interpreter (or REPL) or solve one of the easy beginner problems like finding the greatest common divisor with another interactive site (you can also pick an easier one like this). In a similar vein the katas from helped me get into the language (and become fluent in it).

When you’re ready to write some larger programs of your own I suggest you install a JDK and then the basic build tool Leinigen. Here’s how to do it on unixy OSs (go to the website for Windows instructions):

$ wget
# move if in a dir on your $PATH, like ~/bin
$ mv lein ~/bin
# make it executable
$ chmod a+x ~/bin/lein
# run it once to self-install
$ lein

To edit files I like the excellent cursive plugin for IntelliJ (community edition is fine) or Light Table if you’re not a big IDE fan.

As a starting point for web development I suggest the Luminus micro-framework which packs the best web libraries in one nice template a bit like JHipster generates a nice Spring Boot + AngularJS project. Just type this in a terminal:

$ lein new luminus my-app
$ cd my-app
$ lein run
Started server on port 3000

Although I’m skeptical of large frameworks the Arachne is made by very knowledgeable web developers and will hopefully come out soon and not turn web development into plumbing of some magical components.


If you come this far, take a look at some of the excellent books on Clojure: