Yes, that's the limitation until the value-type DUs arrive in C# 15.

In previous versions of language-ext, I defined Either as a struct with bespoke Match methods to pattern-match. But once pattern-matching appeared in C# proper, it didn't make sense to keep the struct type.

Sounds like C# 15 will be it then? Everything unique about F# will be incorporated.

I guess a lot of how F# structures projects, like file order, or not using nulls, can be done by programming rigor?