> I'm not interested in what "PL (programming language) people" have to say about it. They dislike all generic/parametric polymorphism implementations except their pet language that no one uses.

That's strange. I seem to recall the PL community invented the generics system for Java [0,1]. Actually, I'm pretty sure Philip Wadler had to show them how to work out contravariance correctly. And topically to this thread, Rob Pike asked for his help again designing the generics system for Go [2,3]. A number of mistakes under consideration were curtailed as a result, detailed in that LWN article.

There are countless other examples, so can you elaborate on what you're talking about? Because essentially all meaningful progress on programming languages (yes, including the ones you use) was achieved, or at least fundamentally enabled, by "PL people".

[0] https://homepages.inf.ed.ac.uk/wadler/gj/

[1] https://homepages.inf.ed.ac.uk/wadler/gj/Documents/gj-oopsla...

[2] https://arxiv.org/pdf/2005.11710

[3] https://lwn.net/Articles/824716/

Yeah, it _doesn’t_ apply to C# generics. Basically, if you’ve got List<Person> and List<Company> in C#, those are different classes. In Java, there’s only one class that’s polymorphic. This causes a surprising number of restrictions: https://docs.oracle.com/javase/tutorial/java/generics/restri...

Type erasure is what is wrong with Java generics. It causes many issues downstream.