Why I’m Learning Clojure

Recently, I posed the question of which language I should learn in 2010. The options were Squeak, Common Lisp, Clojure, Groovy… or to make a second attempt with Ruby. I must admit I was veering towards Lisp when I wrote it, but all options were still possibilities. Out of the two Lisp dialects, Common Lisp was probably my preference over Clojure but in the end I decided I would give the latter a shot.

So why Clojure?

Well, the first reason is down to it being a new language. There’s something quite interesting about trying a language in the early days. Since I’m not going to be writing production code with it for the foreseeable future, having a moving target isn’t really an issue. The community surrounding the language is still forming and there’s a chance to watch and interact with a forming and evolving Clojure ecosystem. London also has a Clojure code dojo running, aimed at introducing people to Clojure, which offers an excellent opportunity to help with my learning – and best of all, there’s an overlap with some members of the London Python community. Very handy.

Secondly, Clojure is a Lisp dialect. Lisp has been on my list of languages to learn for a long time, but I’ve always ended up looking elsewhere and my only real experiences with the Lisp world have been trivial at best, and never with “the real thing”. In some ways I guess I’m still following that path, though Clojure feels more like a proper Lisp because at heart it is.

Clojure’s primary environment is of the JVM, an area I’ve only limited experience of. There was a time when Java was appealing to me, but every time I take a second/third/umpteenth look at the language it seems to have accumulated more baggage and bloat. It’s a huge and complex language and ecosystem to get into these days, though very mature and powerful. Clojure would give me an opportunity to delve into the JVM world a bit more.

The language is also making progress in supporting the .NET world. Much as I’m definitely not a Microsoft fan, .NET has grown on me and there’s some interesting work happening with it and the open source Mono implementation. I actually rather like C#, though wish someone would take the core language and move it out of the .NET world – probably a weird idea to some. Anyway, Clojure on the CLR is an interesting idea, so adds a little to the interest because I have to mix things up with .NET developers at work.

So that’s all the fluffy stuff out of the way – what are the other reasons?

Well, Clojure is a functional programming language, which is a current interest of mine. Spurred on by my adventures with Erlang, functional programming is growing on me. It’s also dynamically typed, which has been one of the big revelations during my career, perhaps even more than object-oriented development. It compiles to JVM bytecode; being Lisp, it has read/eval/print which makes language exploration and prototyping a joy; and I can delve into a language with a proper, powerful macro capability.

Clojure is also geared up for the big issue of the now: concurrency. Erlang interested me because of the way it tackled concurrency, something that all programmers are going to have to face up to sooner or later as we live in a multicore world. I like Erlang’s approach a lot, but there are other options out there and I feel it is my duty to examine a few of the options. In particular, the use of Software Transactional Memory (STM) holds an appeal to me. Having used databases the last ten years, transactions feel quite a natural approach for many problems, but definitely not all, and incorporating them into other software domains can only be a good idea. I was considering Haskell at one point to investigate STM, but I must admit to not being a massive fan of parts of Haskell’s syntax so never pursued the idea. With Clojure, I can at last take the chance to delve into STM.

I’m not going to stop learning and exploring Erlang, far from it, but I’m looking forward to adding Clojure to my programming toolkit.

Language for 2010

I’ve been a computer language geek for a long time. Even before I read the excellent book “The Pragmatic Programmer”, I would try and learn a new language every year or two – or at least look at new languages to get ideas. This year I added C# to my repertoire and made a return to learning Erlang, which was supposed to be my original choice for the year until the demands of needing to deal with .NET forced a more pragmatic change.

Even if you never use a new language long-term, just taking a look helps sharpen skills, bring about new insights or even create a renewed appreciation for your current language of choice.

My choice for 2010 is quite tricky, so I need some help in deciding from you, dear reader. The short list is as follows:

Squeak – http://www.squeak.org/

My Smalltalk knowledge is all read and no write, so time I actually learnt the language properly and wrote some code because it looks like such a simple and elegant language. I don’t think knowing and enjoying some Objective-C quite counts, somehow!

Squeak feels like the right way for me to learn Smalltalk. I even downloaded the software a while back, but am ashamed to say I just haven’t installed it yet.

Common LISP – http://clisp.cons.org/

LISP has been on my list (no pun intended) for years. I’ve done a tiny bit of EMACS LISP programming and the Amiga Installer uses a LISP dialect, but neither are really sufficient for me to say “I’ve done LISP”. Eric Raymond (I believe) said LISP was probably the best programming language to learn that you will never use, and I think he’s right. LISP featured things like garbage collection and dynamic typing back in 1958, features that some might believe are relatively new additions to programming languages.

I will, however, say that I don’t agree with people like author Neal Stephenson who insist LISP is the only programming language that can be described as beautiful.

Clojure – http://clojure.org/
Groovy – http://groovy.codehaus.org/

I made a brief look at Java (1.1) in 1996 thanks to a foresighted university lecturer, and again in 2005 when I was unemployed after returning from a season snowboarding. The JVM is pretty cool, but Java has changed a lot since the early days and not always for the better in my opinion. Apart from those two little forays, I’ve avoided the Java ecosystem as an area of interest. Now, however, things are changing. Non-Java languages on the JVM are gaining ground, including Jython and JRuby, but also new languages like Clojure and Groovy are appearing and revitalising the Java world.

Groovy seems to have quite a bit of interest from people in the Python community and, from what I’ve seen, I can understand why. It simplifies a lot of the complexity / boilerplate of Java, adds the power of dynamic typing that smug Pythonistas such as myself take for granted, and the name is suitably non-Enterprisey for me to take notice.

Clojure, on the other hand, is a dialect of LISP for the JVM. This would allow me to look into the JVM ecosystem while learning LISP. I also note there is CLR / .NET support as well, which is interesting – though I doubt I will be able to use it to interact with legacy .NET code at work.

Ruby – http://www.ruby-lang.org/en/

Not strictly a new language for me, but I briefly looked at Ruby on two occasions (notice a Java-like pattern here?). The first time was in 2005 for a possible Ruby developer job. They couldn’t find Ruby programmers so were looking for people with Perl and Python experience – I hadn’t heard of Ruby at the time, but it sounded interesting so I had a quick play with it. The second time was in 2007 when I read the “RESTful Web Services” book.

I must admit, I found Ruby terribly disappointing on both occasions. Please don’t flame me! A language that blends elements of Perl and Python, with some LISP-like tweaks, should be pretty cool, but it just felt syntactically awkward in places. Despite my disappointment, I can see why some people like it and it’s making more of an appearance in places I wouldn’t expect a dynamic language to be mentioned. I should really give it another go.

Now your turn…

So, what language from the list do you suggest I look at and why?