The Case for Groovy

This month's StL JUG features Matt Taylor speaking on TDD with Groovy (tonight!).

Like last month's post on Clojure, I'll play law professor, and try my hand at making some arguments that Groovy is the JVM-based language you should learn (if you can only pick one). Like last time, I'm treating this as an exercise, though this is easy, as I am a Groovy fan.

Grails

Long ago, I would say that the first reason for Groovy was its learning curve. That is still important (see below), but my new first reason is: Grails.

I imagine most readers are familiar with Grails: a Rails-influenced web framework that stands on the shoulders of giants -- namely, Hibernate and Spring. The reason I put this item up front and center is that you can make money with it. There are real jobs to be had here, folks. This is a powerful framework with plenty of momentum.

Griffon, GORM, Gradle, Gant, ...

In addition to Grails, there are several other projects that are intimately related to the Java platform. e.g. Griffon brings Grails-like conventions to Swing apps. Straight from Grails, GORM is a DSL for Hibernate mappings. Gradle is a next-gen build system that stands on top of Ant and Maven, without all that nasty XML. Gant is somewhat similar, used by Grails.

The upshot is that the Groovy community is vibrant and doing many different things: surely something will be useful to your project.

The Language

Up to this point, I haven't written about the language itself. IMO, Groovy seems familiar to Java, but with all of the ceremony stripped away. Tremendous amounts of boilerplate are removed: getters/setters are gone; access modifiers have reasonable defaults; regular expressions are trivially easy; and so on.

But there's more: dynamic typing, closures, the Meta-Object Protocol, and other features provide a rich feature-set that is quite different from a merely trimmed Java.

Tools and Testing

Scott Davis has written an excellent book with the subtitle "Greasing the Wheels of Java". That is spot-on. For XML, web services, scripting Java libraries, etc, Groovy is amazingly useful and effective.

One of these aspects is testing (this is where Matt's talk applies). Groovy has tremendous support for unit-tests, including mocks and stubs. The dynamic nature of the language offers a lot of options. Come on out to the talk to see more on this item.

A Gentle Learning Curve, With Growth

If you know Java, Groovy is extremely easy to learn: in fact, almost all Java will run as Groovy. The curve actually goes downhill (in a good, effortless way).

Now, you may dismiss this. As a reader of this and other fine blogs, you may be confident that you can learn any language, thanks. I'm sure you can. The usefulness of the learning curve is that your work (e.g. a utility) is far more likely to be used by other Java developers. In a team environment, that's important. Groovy is unmatched in this regard: it promotes social computing.

That is, if you want it to do so. If you want to do something wild, Groovy allows you to grow into that as well. In this spirit, it is reminiscent of Python: the curve is always reasonable but seems to climb forever. As mentioned, the dynamic nature of the language will definitely, quickly, take you to places that you haven't been using only Java.

The Upshot

I realize there are no code samples in this post. I apologize. Again, this is a quick list of 'arguments' for learning Groovy as your next language on the JVM. There is a ton of material out there, both in free documentation and in books.

(Full disclosure, some of the following authors are friends.)

For Groovy books, start with either Programming Groovy or Groovy Recipes. For Grails books, pick up either Grails: A Quick-Start Guide or the ultimate reference, The Definitive Guide to Grails.

Either way, give Groovy a shot, or come on out to the StL JUG. It is time well-spent.