SAN FRANCISCO—At its Build developer conference today, Microsoft announced that it was open sourcing a wide array of its .NET libraries and related technologies and creating a group, the .NET Foundation, to oversee the development and stewardship of the open source components.
Perhaps the highlight of the announcement today was that the company will be releasing its Roslyn compiler stack as open source under the Apache 2.0 license. Roslyn includes a C# and Visual Basic.NET compiler, offering what Microsoft calls a "compiler as a service."
Many—though not all—compilers operate essentially as black boxes. They slurp in source code at the front, and spew out executable code at the back. With Roslyn, Microsoft is taking a different approach. The Roslyn compiler can be used as a library. When it reads a piece of source code, it produces an internal representation that third-party code can then manipulate and examine.