instructions.md

Lilly the Lisp Alien is back and doing more cooking! This time they are going to create Lisp Alien Lasagna which is not entirely unlike Human Lasagna.

Lilly will need some functions written to help figure out the timing of the cooking of the lasagna. And each one needs to have good documentation so Lilly won't forget what each one does.

Can you help Lilly write functions to help them time the cooking of the Lasagna?

1. Define the expected oven time in minutes

Define the expected-minutes-in-oven function that does not take any parameters and returns how many minutes the lasagna should be in the oven. According to the Lisp Alien tradition (just like Lilly's parental-unit used to cook), the expected oven time in minutes is 337:

(expected-minutes-in-oven) ;; => 337

2. Calculate the remaining oven time in minutes

Define the remaining-minutes-in-oven function that takes the actual minutes the lasagna has been in the oven as a parameter and returns how many minutes the lasagna still has to remain in the oven, based on the expected oven time in minutes from the previous task.

(remaining-minutes-in-oven 100) ;; => 237

3. Calculate the preparation time in minutes

Define the preparation-time-in-minutes function that takes the number of layers Lilly added to the lasagna as a parameter and returns how many minutes Lilly spent preparing the lasagna, assuming each layer takes 19 minutes to prepare.

(preparation-time-in-minutes 3) ;; => 57

4. Calculate the elapsed time in minutes

Define the elapsed-time-in-minutes function that takes two parameters: the first parameter is the number of layers Lilly added to the lasagna, and the second parameter is the number of minutes the lasagna has been in the oven. The function should return how many minutes Lilly has worked on cooking the lasagna, which is the sum of the preparation time in minutes, and the time in minutes the lasagna has spent in the oven at the moment.

(elapsed-time-in-minutes 3 100) ;; => 157