The rise-and-fall adoption of Scala and Apache Groovy is because their whole rationale for existing was to be a better something. Groovy (2003) tried to be a better Beanshell (1998) by adding closures to it. Beanshell tried to be a better Java (1995) by adding dynamic typing to it. Scala (2003) tried to be a better Java by adding definable operators to it. But when something even better comes along, their rationale for existing disappears. They will try to catch up by adding features later (e.g. Groovy 2's inferred typing to compete with Scala, or its more recent macros to compete with Clojure) but by then the newer language has made a foothold, and it's too late.