[vorg]

> why can't a group of programmers just copy the design of Rails to Java? [...] as of now, there is still no decent web framework for Java that is as easy to use as Ruby on Rails. Why is that? [...] Well, simply, because they can't.

> pretty much all of the Ruby language features come into play in some way. Rail's ActiveRecords [...] Ruby's runtime evaluation features. [...] you subclass ApplicationController [...] importing various mixins [...] attaching a call back [...] Ruby is dynamically-typed and garbage-collected. These features are simply not available in all other languages. Java's meta-programming features, for example, are just not powerful enough to implement a system like ActiveRecords. Rails is only possible because of Ruby.

Groovy and Grails tried to duplicate Ruby and Rails, even having soundalike names. Unfortunately, after its founder was managed out, Groovy (nowadays called Apache Groovy) lost its way and tried to diversify down many roads (e.g. generics, command syntax for Gradle, static type compilation, targeting Android) instead of sticking to its knitting and becoming the best possible JVM dynamic language for software like Grails, even eventually became good at none of its goals. So although it's a no-brainer that Grails would become as popular for the JVM as Ruby became for native apps (heck, Grails even bundles Spring), because of the incompetent project management of Groovy (which doesn't even have a roadmap now), Grails adoption faltered.