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.NET 11 and C# 15 will be released tomorrow. And C# finally gets the feature developers have asked for over a decade 👇 .NET 11 is a Standard-Term Support (STS) release. STS releases now get 24 months of support, so .NET 11 is supported until November 2028. Here are 2 features I'm most excited about. 👉 𝗨𝗻𝗶𝗼𝗻 𝗧𝘆𝗽𝗲𝘀 A union says a value is exactly one of a fixed set of types: public union PaymentMethod(CreditCard, PayPal, BankTransfer); The case types don't need a common base class. The compiler checks that your switch expression handles every case. You don't need a default branch. Add a 4th payment method later → every switch that misses it gets a compiler warning. Before C# 15, you had 3 weak options: • object, which accepts anything • A marker interface or base class, which anyone can extend • A 3rd party library that emulates unions 👉 𝗥𝘂𝗻𝘁𝗶𝗺𝗲 𝗔𝘀𝘆𝗻𝗰 Since C# 5, the compiler has turned every async method into a hidden state machine class. And you paid in latency and garbage collection for each async-await call. In .NET 11, the runtime handles async by itself. According to Microsoft's .NET 11 performance post: → Live stack traces: 13 frames → 5 frames → Sync completion: 21.2 ns and 144 B → 6.2 ns and 0 B → Exceptions through 30 async layers: 51.3 μs → 10.7 μs The best part: the .NET libraries are already compiled with Runtime Async. So part of the speed-up comes for free in every .NET 11 app. Tomorrow, I'll share with 28,000+ developers: → What's New in .NET 11 → What's New in C# 15 → What's New in .NET 11 Libraries → What's New in ASP .NET Core 11 → What's New in EF Core 11 → Breaking changes to check before you upgrade 📌 Subscribe to my weekly newsletter to get it first: ↳ antondevtips.com/newsletter?…