.NET (OK, C#) finally gets union types

#1

Post by ingve » Fri, May 22, 2026, 12:28 PM UTC

.NET (OK, C#) finally gets union types
andrewlock.net

Re: .NET (OK, C#) finally gets union types

#2

Post by munchler » Sat, May 23, 2026, 9:10 PM UTC

F# leads the way and C# slowly catches up, as always. Yet for some reason, C# still gets all the mindshare.

Re: .NET (OK, C#) finally gets union types

#3

Post by hahn-kev » Sat, May 23, 2026, 9:10 PM UTC

I'm glad to finally see this making it's way into C#. Not so much because I want to use unions purely in C#. But because I want to be able to define them when interfacing with other languages.

Re: .NET (OK, C#) finally gets union types

#4

Post by Quarrelsome » Sat, May 23, 2026, 9:11 PM UTC

I mean yes, but also: uh-oh. I'm looking forward to reading some code that is even more confusing than the code I'm already reading.

Not entirely convinced that I see the usecase that makes up for the potential madness.

Re: .NET (OK, C#) finally gets union types

#5

Post by moomin » Sat, May 23, 2026, 9:13 PM UTC

AFAICT, this means you won’t be able to define Either, which is definitely a thing you sometimes want to do.

Re: .NET (OK, C#) finally gets union types

#6

Post by [deleted] » Sat, May 23, 2026, 9:13 PM UTC

[deleted]

Re: .NET (OK, C#) finally gets union types

#7

Post by vips7L » Sat, May 23, 2026, 9:15 PM UTC

Quarrelsome wrote: post #4

I mean yes, but also: uh-oh. I'm looking forward to reading some code that is even more confusing than the code I'm already reading. Not entirely convinced that I see the usecase that makes up for the potential madness.

Union/sum types are generally a good thing. Even Java added them. They tend to be worth “the madness”. Now the rest of all the crazy C# features might be a different question.

Re: .NET (OK, C#) finally gets union types

#8

Post by le-mark » Sat, May 23, 2026, 9:15 PM UTC

I used to see some excitement around .net core several years ago. I haven’t heard or seen much in the wild. Is anyone using .net on systems other than windows nowadays?

Re: .NET (OK, C#) finally gets union types

#9

Post by dgellow » Sat, May 23, 2026, 9:17 PM UTC

vips7L wrote: post #7

Quarrelsome wrote: post #4

I mean yes, but also: uh-oh. I'm looking forward to reading some code that is even more confusing than the code I'm already reading. Not entirely convinced that I see the usecase that makes up for the potential madness.

Union/sum types are generally a good thing. Even Java added them. They tend to be worth “the madness”. Now the rest of all the crazy C# features might be a different question.

What features do you see as crazy?

Re: .NET (OK, C#) finally gets union types

#10

Post by dgellow » Sat, May 23, 2026, 9:18 PM UTC

le-mark wrote: post #8

I used to see some excitement around .net core several years ago. I haven’t heard or seen much in the wild. Is anyone using .net on systems other than windows nowadays?

It’s huge in the game dev world, with Unity and Godot. .net also had a reasonable community on mobile for a while thanks to Xamarin, but I cannot imagine that many people using it for new mobile projects in 2026 (outside of game dev I mean).

It’s a very decent language (I mean C#) and runtime, I wish it had more market share in the startup world.