I built something simliar https://github.com/jonschoning/Unions/tree/master/Unions I went with `object` internally instead of subclasses.

One thing that I like about my lib is that is serializes to json pretty well, and i added some more special-case variants such as accumulative errors (AccResult) and some applicative lifting operations.

Hey I wanted to thank you! I stumbled across your repo a few years ago, when I was looking at more powerful ways to use the C# type system. I ended up pulling a heavily inspired version of your code into a utility library I made (for a zero dependency package).

https://github.com/Matthew-Dove/ContainerExpressions#eithert

Once again - thanks for your contribution to my learning!