The world of software is rapidly evolving, and so is the state of the art of languages and tooling. How should an aging language go about become more relevant over the years, not less? For C# we believe the answer has a couple of components: Be more places, be more open, and evolve aggressively. A revamp of our fundamental compiler infrastructure (lovingly known as “project Roslyn”) has given us a great boost on all those fronts, and also challenged our concept of what a compiler is: an open, interactive, error tolerant language engine that underlies code understanding at all levels of the development experience.

In this talk we’ll look at the big picture of Roslyn, use its open API to build an IDE feature live on stage, and maybe sneak an early look at language features we’re contemplating building on it for the next version of C#.