C# 15 introduces union types, allowing developers to declare values as exactly one of a fixed set of types with compiler-enforced exhaustive pattern matching. The feature addresses limitations of previous approaches by supporting closed, unrelated type sets. Available starting with .NET 11 Preview 2.
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Union types in C# 15
Microsoft ships union types in C# 15 with compiler-enforced exhaustive pattern matching, closing a long-standing gap in the type system.
Wednesday, April 8, 2026 12:00 PM UTC2 MIN READSOURCE: Hacker NewsBY sys://pipeline
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