Today Microsoft has released the Roslyn compiler project to the public, under the Apache open source license. This stunning announcement was made during Build’s second keynote by C# creator Anders Hejlsberg. Roslyn represents the significant investment Microsoft has made in rewriting its C# and VB .NET compilers from scratch while opening up the compilation process to developers to promote better tooling and editor support.
Now the entire project is available on Microsoft’s CodePlex, freely available for use by all developers whether they are on Windows or otherwise. With Git installed, you can obtain the project directly via a clone operation.
If you only want to try out Roslyn, the preview is available on Connect. If you want to truly dig into the code and compile it on your own environment for testing and experimentation, you will need VS2013 Professional or higher, the Visual Studio 2013 SDK, VS2013 Update 2 RC, and the .NET Compiler Platform (Roslyn) End User Preview.
The roadmap listed on Roslyn’s project page lists numerous items under development most of which can be classified as a feature addition or quality improvement. A status page exists to list the current state of new features being written for C# and VB.
Today’s release of key technology at the foundation of .NET marks an important shift in Microsoft’s thinking. While the runtime (CLR) is not open source, the compiler’s visibility should lead to improved benefits for all regardless of their platform. (The Mono project’s CLR allows non-Microsoft platforms to run the code produced by Roslyn.)