A cool thing about this in Erlang (which I think is the same in Prolog) is that the = operator works almost exactly how you would have expected: it binds the va

A cool thing about this in Erlang (which I think is the same in Prolog) is that the = operator works almost exactly how you would have expected: it binds the value but then it asserts the binding’s equality. So once you’ve established x = 7, x = 8 is actually an error! Because you’re right, it doesn’t make sense that at one point x = 7 and later the same x = 8!