The Scala programming language

Scala rationale: "There are hundreds of programming languages in active use, and many more are being designed each year. It is therefore hard to justify the development of yet another language. Nevertheless, this is what we attempt to do here." I am not convinced.

I found Scala while looking up covariance and contravariance on a lazy Saturday afternoon. Scala happens to have variance annotations which are missing from Java 5. It doesn't appear to have const annotations though, which are arguably more widely needed.