I've found Scala to be a really good compromise–it has most of the functional features of Haskell, a wide array of existing libraries, and access to Java librar

I've found Scala to be a really good compromise–it has most of the functional features of Haskell, a wide array of existing libraries, and access to Java libraries when you need them. Plus implicits/typeclasses make it easy to extend otherwise annoying Java libraries to make them easier to use.