Microsoft Roslyn

For decades, this world view has served us well, but it is no longer sufficient. Increasingly we rely on integrated development environment (IDE) features such as IntelliSense, refactoring, intelligent rename, “Find all references,” and “Go to definition” to increase our productivity. We rely on code analysis tools to improve our code quality and code generators to aid in application construction. As these tools get smarter, they need access to more and more of the deep code knowledge that only compilers possess. This is the core mission of the Roslyn project: opening up the black boxes and allowing tools and end users to share in the wealth of information compilers have about our code. Instead of being opaque source-code-in and object-code-out translators, through the Roslyn project, compilers become services—APIs that you can use for code related tasks in your tools and applications.

The transition to compilers as services dramatically lowers the barrier to entry for creating code focused tools and applications. It creates many opportunities for innovation in areas such as meta-programming, code generation and transformation, interactive use of the C# and VB languages, and embedding of C# and VB in domain specific languages.

The Microsoft “Roslyn” CTP previews the new language object models for code generation, analysis, and refactoring, and the upcoming support for scripting and interactive use of C# and Visual Basic. 

Practical Advantages:

• One of the first uses of Roslyn that comes to mind is that of a business rules engine. Prior to Roslyn, evaluating user macros typically involved implementing Visual Basic for Applications (VBA), calling out to the DLR with Ruby expressions, or shelling out to the command-line compiler with dynamically generated Visual Basic or C# code and obtaining the result of running that code. These methods were less than ideal.
• Roslyn will easily allow dynamic compilation and execution of C# and (eventually) Visual Basic code with the Evaluate() function, as demonstrated Eric Vogel's article "Using The Roslyn Scripting API in C#". User macros written in the same language as the application will make it easier for developers to support user macros representing business rules.
• Code refactoring becomes much easier with Roslyn. Prior to Roslyn, the developers of such tools as DevExpress CodeRush and Refactor Pro and JetBrains ReSharper had to recreate much of the compiler operations as a foundation for their products. With Roslyn, refactoring developers can directly take advantage of the existing compiler capabilities. I can imagine the appearance of NuGet packages to install individual refactoring rules once Roslyn is widely available.

Download: Microsoft "Roslyn" NuGet Package