User is probably referencing concepts wich are not "advanced" per si, they are simply recent implementations of type concepts, we should keep in mind that these

User is probably referencing concepts wich are not "advanced" per si, they are simply recent implementations of type concepts, we should keep in mind that these tend to make for not so efficient languages and Haxe is pointed at the other side of that spectrum. User seems to be some sort of Java api aficionado so I wouldn't put much thought to what "advanced features" is a reference to, coming from that background. User should read up on Haxe and may well leave attribution of novelty to correct adjectivation, reads less pedantic in many ways.