Groovy has supported compile-time safety since version 2.0 with the optional @CompileStatic annotation. It's one of the few languages where you can mix static and dynamic typing, even within the same class. With this annotation enabled, you get pretty close to pure Java performance but with 1/5 the lines of code in some case.

For something like Android, running Groovy with CompileStatic enabled by default would make a lot of sense.