There are certainly cases which aren't expressible(things which require kinding, for example) but your examples aren't a problem. Both tuples and functions can

There are certainly cases which aren't expressible(things which require kinding, for example) but your examples aren't a problem. Both tuples and functions can be represented using System F, and thus can be completely transposed into C# generics. I believe you don't understand C# generics and you should look closer at the fundamental type calculus.