It's not, unfortunately. Myself and another have started on an exhaustive pattern matching library that utilizes implicit conversion operators, type inference,

It's not, unfortunately. Myself and another have started on an exhaustive pattern matching library that utilizes implicit conversion operators, type inference, lambdas, and a well designed fluent interface to provide support for it in C#. Check out, https://github.com/Jagged/OneOf https://github.com/Jagged/OneOf Distributed as DiscU on NuGet.