Retlang is a robust library for writing highly concurrent applications. The library borrows part of its name and design from Erlang.

Jetlang provides a high performance java threading library. The library is based upon Retlang.
The library is a complement to the java.util.concurrent package introduced in 1.5 and should be used for message based concurrency similar to event based actors in Scala.

Concurrent programming library written in Groovy, providing simple programming models for complex multi-threaded tasks

Dierk Koenig