So if you add "EVAL_AS_Y{ ... }" core primitive into X, it becomes strictly more expressive as Y until you add "EVAL_AS_X { ... }" to Y: then they become exactl

So if you add "EVAL_AS_Y{ ... }" core primitive into X, it becomes strictly more expressive as Y until you add "EVAL_AS_X { ... }" to Y: then they become exactly as exressive as each other.