Cω

Cω (also Cw or Comega) is an experimental extension of C#, developed by WebData team of Microsoft SQL Server in collaboration with Microsoft Research. Cω combined two earlier projects — Polyphonic C# which implements asynchronous multithreading and X# or Xen which allows to work with XML and databases as if they were regular data types collections, without any APIs or libraries.

Cω won’t be released as a separate commercial product. Its compiler is available as free preview, and the ideas tested in it are used to create LINQ extensions. Besides, multithreading constructs have been released as Joins Concurrency Library for C# and other .NET languages.