02 December 2011

I've spent some of my spare time in the past few weeks building an abstract rock garden in HTML/Canvas backed by Clojure's Noir framework at rocksandsand.com (source), and I'm going to share some of my experiences here.

I'm really excited by Noir as a framework as it's the first Clojure framework that has a strong opinion about a lot of the things that really matter to a productive web framework.

Let's dive in.

Noir's hello world is what you'd expect in a post-sinatra world:

Where noir really gets interesting is in the tools, convenience, and opinions it brings.

One design choice in noir that makes it practical is the presence of CLI code generation, such as lein noir new. The lein-noir plugin (for clojure's leiningen build system) functions much like rails s.

Noir actively tries to make a bunch of simple web development tasks easy. It's easily the Clojure framework that has the most 'batteries' included. You get things like automatic code-reloading on page refresh, built in lein commands to start up a server in both production and dev mode, a preset folder structure, and a few other such nice opinionated ways of doing things.

Moving on from there, you'll notice your src folder contains two folders 'models' and 'views'. Here's where you'll first notice one of Noir's greatest departures from most other web frameworks. There are no controllers by default (you can read the mailing list thread on why if interested). You wind up with combinations of controllers, views, and routes that--while initially scary--are actually quite elegant. An example of a more complex Noir view:

For a small app like Rocks and Sand, this sort of thing works well, it's more reasonable than splitting such stuff across 3 separate files. Whether it scales up to a large app however, is something I'm still on the fence about.

Views in Noir are not mandated to use any particular language, but Hiccup is by far the most popular solution, and is one of my all time favorite template languages. And it's nothing but clojure vectors and maps! Here's a quick example:

Models in noir are simply straightforward Clojure namespaces, if you want to, noir ships with a validations library you can use with it.

While my experience with Noir is obviously limited I have a list of praises and recommendations for it:

  • Coupling of Routes -> Controllers -> Views is nice for small stuff, I'd probably decouple them more in a larger app. Luckily, if you really want, there's no reason you can't just do that by your own convention. Noir won't get in your way.
  • Models are really bare bones, but have a nice little validation library. Not as complete as Rails', but quite easily extended
  • WebSockets are more and more important these days. Tighter integration with Aleph (defsocket anyone?) would be great. A clojure framework that supports building combination synchronous / asynchronous apps would be awesome. While this is possible, the sugar that Noir's brought to Compojure could be extended to Aleph.
  • The integrated util packages (S3, App Engine, Crypt, Etc.) are awkward and should be in separate jars.
  • The ecosystem is still immature.I can still get more functionality out of Rails per hour due to its great community. However, for side-projects I'll be using noir. Additionally, for data-heavy web-services (like a JSON only backend) something like Noir is great!
  • I wound up writing my own JSON based configuration package. Config files are part of every real web-app, and I think a good config package (preferably with deployment environment (prod/staging/dev) built in.

All in all Noir is exactly what Clojure's been needing to move to the next level in the world of web-apps. It's a beautiful framework, with a few odd opinions, but in generally it's a great way to get a small web-app off the ground. I'd recommend getting started by checking out the Noir homepage, and maybe even diving into the source my rock garden app.

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