Total agreement generally, but I wanted to mention that the Any -> X downcasting is trouble sometimes. It is difficult to do this in a type-safe way (e.g. witho

Total agreement generally, but I wanted to mention that the Any -> X downcasting is trouble sometimes. It is difficult to do this in a type-safe way (e.g. without accidentally introducing holes) and if you have typecasing universally then you lose parametricity, one of the most powerful tools in any polymorphic type theory.