> OK, so you define effect-freedom using the language's equality operator. Not the runtime equality testing operator. Rather, the language's static notion of c

> OK, so you define effect-freedom using the language's equality operator. Not the runtime equality testing operator. Rather, the language's static notion of contextual equivalence. It just happens to be the case that most high-level languages provide a built-in equality testing operator that works on primitive types, returning `true` iff its operands are contextually equivalent values. > I think assembly language and BASIC would still qualify as effect-free I don't even know what a good notion of contextual equivalence for any assembly language would be. As for BASIC, I haven't used the old ones, so I can't comment on them. I've used Visual Basic, which most certainly has effectful procedures.