dotNET (OK, C#) gets union types

Re:dotNET (OK, C#) gets union types by goto11 on Saturday May 23, 2026 @07:29PM (#48252647)

You cant have a `type Foo = String | Strimg` in Haskell either.

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Re:dotNET (OK, C#) gets union types by bertylicious on Saturday May 23, 2026 @11:12PM (#48253982)

But you can have an `Either String String` which is what GP was talking about.

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Re:dotNET (OK, C#) gets union types by bertylicious on Sunday May 24, 2026 @02:54AM (#48255092)

My mistake. I see my oversight now. `Either String String` is not equivalent to `String | String`, but to `Left String | Right String`. The same must be done for the C# version.

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Re:dotNET (OK, C#) gets union types by goto11 on Sunday May 24, 2026 @03:35AM (#48255296)

Yes, you must have individual constructors for the left and right cases in order to distinguish them. In C# you would use two distinct record types for this. Haskell’s syntax is more concise though, since you define the constructors inline in the declaration of the sum type.

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