Java is no longer alone on the JVM. It now has to share space with its younger siblings JRuby, Jython, Groovy, Clojure, Scala and many others. Each new language has its own set of advantages and disadvantages compared to Java, and its own niche in which it performs best, but Scala in particular is gaining momentum.
In this presentation to the San Francisco Java User Group on February 16, 2012, Marakana's own Dan Rosen introduces Scala to Java developers and shows off some of its expressive power -- higher-order functions, type inference, and pattern matching -- by building a simple web service. You'll never look at Java the same way.
. Since the section on monads was not included in this presentation, consider checking out this recent video primer on monadic design.