Every now and then I like to sit in a coffee shop on a Sunday and focus on writing some code. This weekend I had the pleasure of spending this geeky time with a colleague, Chris Ford(twitter).

Chris has gotten me interested into an open source toolkit for creating sounds and making music called Overtone. Here’s a talk about demonstrates functional composition using clojure through music and overtone.

That talk made me want to play with overtone. Here’s the diary of my workstation setup.

Leiningen

Thinking I know what I’m doing I say “So, Overtone is in Clojure, right? So I’ll first install that.”. To which he replied “No, you need to install Leiningen.”. What?! I want to install clojure, why do I need this oddly named tool? Already my world has been turned upside down.

Leiningen is a package manager for Clojure. I can’t say I understand completely what it’s doing, but when I did a sudo port install leiningen I saw Maven was being installed. Chris calmed me down and said that lein hides the pain so I don’t have to worry about it.

Sure enough, the install works. I run lein new mucmusic and a simple project structure is setup for me. I updated the project.clj to refer to the 1.4.0 version of Clojure.

I then run lein repl and see the package manager at work. It downloads Clojure for me and I’m in a repl. I try the most basic thing I know (+ 1 1) and it works! I can only imagine what’s going on behind the scenes. I find it interesting that a package management tool is responsible for obtaining the language you’re going to develop in. It makes a whole lot of sense actually. It’s sort of like virtualenv, but not quite.

Clojure

Since I’m still coming to grips on writing code in Clojure I can’t comment on the language, but what I really like so far is how accessible the documentation is. Simply evaluating (doc +) will print the documentation for ‘+’ function and (source +) prints out the source code. The REPL made it very easy to get started.

One thing that tripped me up was using a namespace I had defined. I learned the the ’ character is used to indicate the following text is a symbol and not to be evaluated. Also, the first project I created had an underscore in it. In order to use that namespace I had to use a hyphen when using it.

Overtone

Happy that I can write and evaluate Clojure code it was time to setup Overtone. This part was really nice. All I did was update the project.clj file and added the overtone dependency. The next time I ran lein repl it downloaded overtone and set everything up for me.

In the repl I loaded overtone via (use 'overtone.live) and here’s the output:

reply.eval-modes.nrepl=> (use 'overtone.live)
--> Loading Overtone...
--> Booting internal SuperCollider server...
--> Connecting to internal SuperCollider server...
--> Connection established

    _____                 __
   / __  /_  _____  _____/ /_____  ____  ___
  / / / / | / / _ \/ ___/ __/ __ \/ __ \/ _ \
 / /_/ /| |/ /  __/ /  / /_/ /_/ / / / /  __/
 \____/ |___/\___/_/   \__/\____/_/ /_/\___/

    Collaborative Programmable Music. v0.8

Hello ThoughtWorks, just take a moment to pause and focus your creative powers...

Woah! Booting internal SuperCollider server? Is Clojure so powerful that I can run my own atom smasher? Turns out the answer is unknown on that, but what overtone.live does is smartly start up SuperCollider which is “an environment and programming language for real time audio synthesis and algorithmic composition”. Ahh! So overtone needs this to actually create audio.

I continue to follow the README and make my first sound.

(demo (sin-osc))

This code rewards me with the beautiful sound that is a sine wave. Curious as to what demo and sin-osc do I load up the docs in the repl.

overtone.live/demo
([& body])
Macro
  Listen to an anonymous synth definition for a fixed period of time.
  Useful for experimentation.  If the root node is not an out ugen, then
  it will add one automatically.  You can specify a timeout in seconds
  as the first argument otherwise it defaults to *demo-time* ms. See
  #'run for a version of demo that does not add an out ugen.

  (demo (sin-osc 440))      ;=> plays a sine wave for *demo-time* ms
  (demo 0.5 (sin-osc 440))  ;=> plays a sine wave for half a second
nil
user=> (doc sin-osc)