static-dispatch

Which the inferencer probably can't do because of how dynamic standard-class can be. Also, if we want to get pedantic, method-dispatch does not dispatch on types in Common Lisp, but rather via EQL or the class of the argument. Since sub-classes can be made (and methods added or even removed) after a method invocation is compiled, there is no feasible way in a typical lisp implementation[1] to do compile-time dispatch of any type that is a subtype of standard-object. Now none of this prevents you from extending lisp in such a way that lets you freeze the method dispatch (see e.g. https://github.com/alex-gutev/static-dispatch), but "a modern compiler will jmp past the type checks" is false for all of the CLOS implementations I'm familiar with. 1: SICL is a research implementation that has first-class global environments. If you save the

CLOS is more than fast enough for games (see e.g. Kandria, there are comments on HN about it, though it's easy enough to do one's own benchmark and see how easy it is to get hundreds of frames per second even with thousands of objects updated and drawn through methods every frame), and if you do have some numerical generic functions in a tight loop you can optimize them further with libraries like https://github.com/alex-gutev/static-dispatch The book Object-Oriented Programming: The CLOS Perspective (1993) even includes as its final chapter/paper "Efficient Method Dispatch in PCL" which is essentially a memoization technique, so it's been a concern (or because of such techniques, not the biggest concern) for a long time. The dev experience of using defstruct is bad enough when I want to change something about it that I just default to de