Working on an analogy for comparing forms of programmatic evaluation: • **Eager evaluation:** Grab-and-Go sandwich. Made ahead of time, ready the instant you want it. Startup costs; work may be thrown away. • **Lazy evaluation:** Subway sandwich. Made when you ask for it. Less waste, but your progress is blocked while you wait. • **Async evaluation:** Doordash sandwich. Submit your order, wait for it to arrive. You can do something else while you wait, but the wait might be long. #programming