What's the coolest thing coming in the next version of C#?
C# 15 will introduce union types, shipping in November 2026
“It's like it's either a cow, a sheep, or a pig, and then uh use that type uh in a strongly typed fashion.”
C# 15 will add union types, allowing strongly typed handling of a closed set of unrelated types with switch support. The feature is already in preview via Visual Studio and VS Code, with general availability planned for November. This is a language evolution announcement with no meaningful AI industry signal.