dotNET (OK, C#) gets union types

a day ago

Unions are a new feature in C# 15 and .NET 11, allowing types to represent multiple different cases.
They are useful for scenarios like handling different OS record types (Windows, Linux, MacOS) without needing a common base class.
The union keyword creates a union type, which can be instantiated via constructors or implicit conversions.
Switch expressions provide a safe way to handle union types, with compiler-enforced exhaustiveness checks.
Union types are implemented as structs with an IUnion interface and a Value property holding the inner object.
Custom union implementations can avoid boxing for performance by using TryGetValue methods for each case type.
Features like union member providers, closed enums, and closed hierarchies are planned for future releases.

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