Panu Oksala • 4/18/2026

A first look at C# unions in .NET 11

This article explores the new union types feature coming to C# in .NET 11. It provides a step-by-step guide on setting up the preview SDK, enabling preview language features, and adding a polyfill to make unions work. The author demonstrates a simple union example representing vehicle types (Car, Truck, Motorcycle) and discusses why unions can be a better alternative to inheritance or interfaces. It also notes a current limitation with top-level statements. This is a technical tutorial relevant to software development and C# programming.

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#polyfill #c #union types