My line of thought had been that doing so doesn't restore execution context. But it dawns on me that without the ability to mutate variables that doesn't have t

My line of thought had been that doing so doesn't restore execution context. But it dawns on me that without the ability to mutate variables that doesn't have the same relevance. Still, doesn't it throw the de bruijn indexes off? Or am I wrong about that as well? Lambda calculus makes my head hurt.