Dynamically typed languages have recently turned out to be suitable for developing specific scenarios where dynamic adaptability or rapid prototyping are important issues. However, statically typed programming languages commonly offer more opportunities for compiler optimizations and earlier type error detection. Due to the benefits of both approaches, some programming languages such as C# 4.0, Boo, Visual Basic or Objective-C provide both static and dynamic typing. We describe the
programming language that supports both type systems in the very same programming language. The main contribution of
is that it keeps gathering type information at compile time even over dynamically typed references, obtaining a better runtime performance, earlier type error detection, and an intuitive combination of statically and dynamically typed code.