[viraptor]

Yup, that doesn't seem to be a real restriction. Here's a comment on a roslyn issue for dotnet: https://github.com/dotnet/roslyn/issues/2212#issuecomment-98...

> Of course it could be implemented type-erased style, but that's an unpleasant can of worms.

> If it were implemented like C++ templates, it would be a source level feature, meaning you can't have higher kinded polymorphic methods in assemblies. I think we can reach consensus that such a feature would only pollute the language.

> If it were implemented like Java generics, it would lead to all sorts of nonsense. For example you couldn't do typeof(M<>) inside the hkpm, since the type has been erased.

And then a complex-but-good implementation idea follows. Type erasure is not necessary in this case.

[zzygan]

The complexity is exactly is issue. So while it’s possible to implement on the .net runtime without type erasure, it’s hard.

Plus the only reason type erasure is bad is if you want reflection. Which in FP languages with a solid type system isnt idiomatic and safe anyway. Edit: value types are one other reason for not using erasure but Can be done other ways