OK, so there are quite a few people using Java these days. But as the language nears two decades of age, it isn't exactly the coolest option out there. Many of us are excited about dynamic languages with some functional features like Ruby or Python, even though we spend our days using Java.

So why is it that the adoption of Groovy has been so slow? It seems that Groovy offers much of the benefits of Ruby and Python, but it is far easier to transition a Java shop to Groovy. Even if performance were the concern, it seems that many would want to use Groovy for testing the production Java code. Or use Groovy/Grails for internal apps in which performance concerns are minimal. Or for writing one-off scripts to generate code.

Yet Groovy languishes outside of Tiobe's top 50 languages, for reasons that are unclear to me.

I have been using Groovy and Grails professionally for about four months, and it has been an excellent experience, such that I hate to think about going back to the Java/Spring/Hibernate model.

Does anyone have any sense on why we are not seeing more significant migration from Java to Groovy?

Note that I'm not asking why Java developers are still using Java for new projects. My question is: Why is it that most Java Developers are still not using Groovy at all.

Edit: I am assuming that all good developers see the utility of dynamic typing and higher order functions for some programming tasks. (Even if it is deemed inappropriate for production code.)