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Discriminated unions proposals overview (might come in C# 16) (github.com)
submitted 1 year ago by vermaterc@lemmy.ml to c/csharp@programming.dev
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A discriminated union is a data structure that can hold one of several distinct types of data. This type-safety allows developers to build complex data structures, like API responses or state machine events, and ensures all possible cases are handled, preventing runtime errors.

This is a proposal that might come in C# 16

If you prefer this as a video explanation then Nick Chapsas made one: https://www.youtube.com/watch?v=tD46WVJ2h9I

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[-] sirdorius@programming.dev 1 points 1 year ago

Looking good. Especially looking forward to unions backed by a struct.

[-] soc@programming.dev 1 points 1 year ago* (last edited 1 year ago)

This exactly what I described in 2021, so I'm pretty happy seeing other languages also going this route.

Sadly, they also don't have a solution for the follow-up question that naturally falls out if this approach -- how to "unbox" generic types such that they can be used directly and don't need some additional type to hold it, i.e.

union Option[T] of T, None // None defined elsewhere

instead of

union Option[T] of Some[T], None // Some & None defined elsewhere
this post was submitted on 30 Aug 2025
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