Agents with explicit messages are much closer to Smalltalk OO than virtual methods implemented via dispatch tables, with statically typed arguments. OOP has it

Agents with explicit messages are much closer to Smalltalk OO than virtual methods implemented via dispatch tables, with statically typed arguments. OOP has its place. I think it's decent in the small - when you're dealing with data structures which inherently have state and need to maintain invariants - and it's decent, in the agent form, in the large, where you have encapsulated state in separate agents which communicate with one another using messages, as long as you have other actor-model things like fault tolerance. It's in the middle, when you're trying to write a big app filled with communicating mutable objects with lots of mutual references, that things can get pretty sticky. My experience is that it's better to favour complete knowledge of concrete types than to minimize knowledge of concrete types and leave them open to extension. That is, pattern matching is generally preferred to polymorphism and it's better to get a compilation error when you add a new subtype than it is to try and always squish your new subtype into a polymorphic interface straitjacket to use virtual dispatch instead. There are other problems with object orientation, particularly the way it produces very pointerful code and isn't friendly to - doesn't take advantage of - high latency high bandwidth memory.