As Sing# (http://en.wikipedia.org/wiki/Sing_sharp ) and Chapel, Scala is one of the languages to be followed more, because they share some of future purposes of D2/D3.
A small presentation about the close future of Scala (it's not a general introduction to Scala): "Scala -- The Next 5 Years" by Martin Odersky: http://www.scala-lang.org/sites/default/files/odersky/scalaliftoff2009.pdf Sing# has a complex and advanced core, and I haven't found good tutorials about it. I have found a confusing document about Spec#, that's a limited father of Sing#. I think the only significant improvement of Spec# over D2 is that Spec# contains a kind of inference engine that probably processes/uses contracts and class invariants quite better than D2 (probably in a similar way to Eiffel): http://channel9.msdn.com/wiki/specsharp/specsharpobjectprimer Bye, bearophile
