This is Fan - An introduction to the Fan programming language.

Fan is an OO, functional language designed to cross compile to both the Java and .NET platforms. Its designed to be a real-world language that enables developers to do more in less. It boasts a familiar Java/C# style syntax, static and dynamic typing, closures, mixins, elegant APIs, concurrency features such as immutability and message passing, and a declarative programming syntax for serialization.