> The goal for Valhalla is value types, reified generics if they ever happen is still open.

But if they want the List<int> use case to be fast they basically have to keep this information at runtime and will have to make changes to how objects are laid out in memory. I'm not sure there's a good way around that if you want List<int> to be backed by an int[] and `get` returning an int instead of an Object. This may or may not be available to developers and remain internal to the JVM in the beginning, but I think it's necessary to enable the desired performance gains.

They also state on the website: »Supplementary changes to Java’s generics will carry these performance gains into generic APIs.«