so, assuming the declared fact "x = y", whenever you see "x" you could substitute "y" (and vice versa), and it would make no difference whatsoever? You don't h

so, assuming the declared fact "x = y", whenever you see "x" you could substitute "y" (and vice versa), and it would make no difference whatsoever? You don't have to worry about whether it is defined yet, or if it has been changed, or if it is really a copy (not a reference/pointer). I intuitively think in terms of an execution model, so this is hard for me (even though it's actually less complex with less to worry about). Thinking of it as "declarative" seems helpful, thanks...