> Unless by using the CLOS you mean having to explicitly opt-in by using classes, multiple dispatch, multiple inheritance, generic functions, the MOP and all th

> Unless by using the CLOS you mean having to explicitly opt-in by using classes, multiple dispatch, multiple inheritance, generic functions, the MOP and all that weird stuff. Yes, that's what I meant. The fact that the CL type system maps into the class system doesn't mean we all code OOP. If you want to argue semantics, sure.. SBCL will generate _very_ different code for fixnums vs general objects, so much so that claiming that (+ 1 2) is using CLOS makes no sense.