title: In which language is the C# compiler written?
body: <p>I looked at the source code at <a href="http://referencesource.microsoft.com/" rel="noreferrer">http://referencesource.microsoft.com/</a>, and it appears all the source code is in C#.</p>
  
  <p>I also looked at the source code for the new C# compiler platform (<a href="https://en.wikipedia.org/wiki/.NET_Compiler_Platform" rel="noreferrer">Roslyn</a>), and it is also in C#. How is that possible? Is C# language compiler written in C#? Or am I missing something obvious? If C# compiler is written in C# then how does it work?</p>