A Look at the Main JVM Languages Today, February 14, 2012 The JVM hosts an increasingly wide array of languages. Here we compare the prominent ones, mourn those that have come and gone, and celebrate newborn languages clamoring for attention.
JRuby and Mirah
These two languages, designed by the same team, bring the Ruby language to the JVM. The language features have all been ported, and it's now possible to run Ruby on Rails on the JVM. Interoperability between Ruby and the Java environments is excellent and runs equally well in both directions: Running Ruby gems or Java libraries is straightforward.
Mirah does the same thing as JRuby, but brings over fewer conventions from the Ruby language. This allows Mirah to ship as a single JAR file without bringing over many of the packages needed by JRuby to completely emulate the Ruby environment. Recently, Dr. Dobb's has covered Mirah and JRuby.