JavaScript: Functional Programming for JavaScript Developers

Lazy instantiation

If you go into a higher-end coffee shop and place an order for some overly complex beverage (Grande Chai Tea Latte, 3 Pump, Skim Milk, Lite Water, No Foam, Extra Hot anybody?) then that beverage is going to be made on-the-fly and not in advance. Even if the coffee shop knew which orders were going to come in that day, they would still not make all the beverages up front. First, because it would result in a large number of ruined, cold beverages, and second, it would be a very long time for the first customer to get their order if they had to wait for all the orders of the day to be completed.

Instead coffee shops follow a just-in-time approach to crafting beverages. They make them when they're ordered. We can apply a similar ...