While the C# compilers have been open source since 2014, now available in the dotnet/roslyn repository, but the dotnet/csharplang split off provides a dedicated public space for the innovation and evolution of the C# language. And the dotnet/csharpstandard repo now available on GitHub will be the working space for the ECMA C# standards committee, TC-49-TG2 which is still responsible for creating the proposed standard for the C# language.
Thus, the C# language innovation and feature design through to implementation and standardization will now take place in the “open” with the contributions all public.
Innovation and evolution of the C# Programming language
Microsoft had earlier open sourced C# compilers, and now, there are now about three such repos dedicated to the C# programming language:
The move means that developers can now see the work in progress and work to incorporate features also as it is taking place.
And it'll be easier to ask questions among the design team, the compiler implementers, and the committee; as the conversations will also be public. The changes planned for the coming months include: Issues in csharplang and dotnet/docs for the spec text will move to the new dotnet/csharpstandard repo.
The C# spec on docs.microsoft.com is going to be replaced with the version from the standards committee. And the C# 6 draft spec removed from the dotnet/csharplang repo, once the proposed C# 6 draft is published on docs.microsoft.com.