Do you have a comparison to other libraries like https://github.com/louthy/language-ext

Yours looks a lot more idiomatic to C# (hence acceptable for a mixed code base) but the above linked more "systematic". Not that I have used any or have any competence.

I normally do a much deeper dive into the existing ecosystem before I write a library like this. In this case, I tried a few of the popular packages, but in the end decided my own pursuit of the exact types I wanted was more interesting. So, I just went for it.