Assignment 8

Due Date Monday 02/11 at 9pm

Purpose To design functions over lists and compound data.

(define-struct shopping [item others])

; A ShoppingList is one of:

; - "no items"

; - (make-shopping GroceryItem ShoppingList)

; and represents a list of items to buy at the grocery store

(define-struct item [name price quantity])

; A GroceryItem is a (make-item String PositiveRealNumber Nat)

; - where name is the name of the item

; - price is the item's price at the nearest grocery store

; - and quantity is how many of the item you want to buy

Exercise 1 Provide examples and a template for each data definition above.

Exercise 2 Design a function total-cost which, given a ShoppingList, produces the total cost of purchasing everything on the list. You may assume that the price given for an item is for only 1 of that item.

Exercise 3 Design a function that accepts a ShoppingList and produces an image of the names of the items on the list above each other. Items at the front of the shopping list should appear above the others. An empty shopping list should be drawn with an empty-image. Above all of them (no matter how many items are on the list), the text "Shopping list:" should appear in "blue".

Exercise 4 Design a function that accepts a ShoppingList, a String (representing the name of an item), and a PositiveRealNumber (representing the price of an item). If the item is already on the list the function should add 1 to the quantity for that item (you do not need to check if the price is the same). If the item is NOT on the list, it should be added with a quantity of 1 and the given price. Your function should NOT go through the ShoppingList more than once.

Exercise 5 Design a data definition for an Event. An event has a name (e.g. "Women's march") and a date containing a year, month, and day. Remember to follow all the steps of the data design recipe.

Exercise 6 Design a data definition for a Timeline. A Timeline is either an Event or it has an Event and another Timeline representing events that happened after that first event. Remember to follow all the steps of the data design recipe.

Exercise 7 Consider the following data definitions:

(define-struct letter [from to weight])

; A Letter is a (make-letter Address Address PositiveRealNumber)

; - where from is the address the letter is from

; - to is the address to send the letter to

; - and weight is the letter's weight (in ounces)

(define-struct addr [street num zip])

; An Address is a (make-addr String Nat ZipCode)

; - where street is the name of the street

; - number is the house number on the street

; - and zip code is the zip code of the address

(define-struct zip [a b c d e])

; A ZipCode is a (make-zip Digit Digit Digit Digit Digit)

; representing a 5-digit zip code

; A Digit is a Nat in the range [0,9]

Design a function update-zip-digit which, given a Letter, a Digit, and a natural number in the range [1,5] (representing one of the 5 zip code digits) updates the zipcode in the "to" address by changing the given field to have the given Digit. We have provided one test (which is most definitely not sufficient testing) to help explain this:

(define ZIP-BOSTON (make-zip 0 2 1 1 5))

(define ZIP-ILLINOIS (make-zip 6 0 2 0 8))

(define ZIP-IL-MISTAKE (make-zip 6 0 0 0 8))

(define ADDR1 (make-addr "Huntington Ave" 360 ZIP-BOSTON))

(define ADDR2 (make-addr "Clark St" 633 ZIP-ILLINOIS))

(define ADDR2-MISTAKE (make-addr "Clark St" 633 ZIP-IL-MISTAKE))

(define LETTER-BAD (make-letter ADDR1 ADDR2-MISTAKE 5))

(define LETTER-GOOD (make-letter ADDR1 ADDR2 5))

(check-expect (update-zip-digit LETTER-BAD 2 3) LETTER-GOOD)

You do not have to provide the steps of the data design recipe for the given definitions. However, doing so will definitely help you to design the function.