Out: Monday, September 29, 2014
Due: Monday, October 6, 2014 at 600pm local time
The goal of this problem set is to help you design functions that deal with lists.
Remember that you must follow the design recipe. Your deliverables include the data analysis (including template), contract and purpose header, examples, design strategy, code, and tests. You must also include your laboratory notebook.
As you did before, download a copy of extras.rkt and put it in the folder with your solutions. Download any other files that are needed for each problem. Put necessary provide and require directives at the top of your file, as you did before.
The inventory satisfies the invariant that there are no duplicates: any isbn appears at most once in the inventory. In this problem set, we don't provide any way to add or remove books (ISBNs) from the inventory, although we do model changing the number of copies of an ISBN that are currently in stock.
You also need to deal with orders. An order is a list of line items. A line item consists of an ISBN and the quantity ordered. The quantity ordered is always a positive integer. Here is an example of an order; each line of the table is a line item. Here is an example of how an order might be displayed as a table.
Like the inventory, an order will contain no duplicate line items: any isbn will occur at most once in an order.
Also, for this problem, we introduce the Data Definition MaybeInteger
;; A MaybeInteger is one of: ;; -- Integer ;; -- false
Design the following functions.
All functions that return an inventory should return an inventory with the books in the same order they were in the argument.
Your solution should provide the following functions:
inventory-potential-profit : Inventory -> Integer GIVEN: an inventory RETURNS: the total profit, in USD*100, for all the items in stock (i.e., how much the bookstore would profit if it sold every book in the inventory). inventory-total-volume : Inventory -> Real GIVEN: an inventory RETURNS: the total volume needed to store all the books in the inventory price-for-line-item : Inventory LineItem -> MaybeInteger GIVEN: an inventory and a line item RETURNS: the price for that line item (the quantity times the unit price for that item). Returns false if that isbn does not exist in the inventory. fillable-now? : Order Inventory -> Boolean. GIVEN: an order and an inventory RETURNS: true iff there are enough copies of each book on hand to fill the order. If the order contains a book that is not in the inventory, then the order is not fillable. days-til-fillable : Order Inventory -> MaybeInteger GIVEN: an order and an inventory RETURNS: the number of days until the order is fillable, assuming all the shipments come in on time. Returns false if there won't be enough copies of some book, even after the next shipment of that book comes in. EXAMPLES: if the order contains one book that is out of stock, with a reorder status showing 2 days until delivery, then the order is fillable in 2 days. If the order is for 10 copies of the book, and the next order consists of only 5 books, then the function should return false. price-for-order : Inventory Order -> NonNegInteger RETURNS: the total price for the given order, in USD*100. The price does not depend on whether any particular line item is in stock. Line items for an ISBN that is not in the inventory count as 0. inventory-after-order : Inventory Order -> Inventory. GIVEN: an inventory and an order WHERE: the order is fillable now RETURNS: the inventory after the order has been filled. increase-prices : Inventory String Real -> Inventory GIVEN: an inventory, a publisher, and a percentage, RETURNS: an inventory like the original, except that all items by that publisher have their unit prices increased by the specified percentage. If the increased price is a non-integer, it may be either raised to the next integer price, or truncated to the next lowest integer price in USD*100. EXAMPLE: (increase-prices inventory1 "MIT Press" 10) returns an inventory like the original, except that all MIT Press books in the inventory have had their prices increased by 10%. Also provide the functions: make-book (9 arguments) make-line-item (2 arguments) The arguments to these functions should appear in the same order as they do in the problem statement. reorder-present? : ReorderStatus -> Boolean RETURNS: true iff the given ReorderStatus shows a pending re-order. make-empty-reorder : Any -> ReorderStatus Ignores its argument RETURNS: a ReorderStatus showing no pending re-order. make-reorder : PosInt PosInt -> ReorderStatus GIVEN: a number of days and a number of copies RETURNS: a ReorderStatus with the given data.
Before you turn in your solution, make sure it passes the tests in ps03-inventory-qualification.rkt. As before, download this file, save it in your set03 directory, and run it to qualify your program for grading. Be sure to commit this file to your repository so we know that you've done this correctly.
For what it's worth, students in previous semesters have solved variations of this problem in a median time of 12-15 hours.
Your program should provide the following functions:
run : Any -> World GIVEN: An argument, which is ignored. EFFECT: runs the world at tick rate of 0.25 secs/tick. RETURNS: the final state of the world. Note that the world does not respond to time passing, so the tick rate doesn't make a difference. initial-world : Any -> World GIVEN: An argument, which is ignored. RETURNS: a world with no balls. world-after-key-event : World KeyEvent -> World RETURNS: the world that should follow the given world after the given key event. world-after-mouse-event : World Integer Integer MouseEvent -> World GIVEN: A world, the location of a mouse event, and the mouse event itself RETURNS: the world that should follow the given world after the given mouse event at the given location. world-balls : World -> ListOfBalls GIVEN: a world, RETURNS: the list of balls that are in the box. ball-x-pos : Ball -> Integer ball-y-pos : Ball -> Integer GIVEN: a ball RETURNS: the x or y position of its center, respectively. ball-selected? : Ball -> Boolean GIVEN: a ball RETURNS: true if and only if it is currently selected
Note: if any of these functions are implemented as selectors on structs, then you don't need to provide the design recipe deliverables for them.
If any function is just a renaming of an extractor, for example
(define-struct ball (x y ...)) ... (define (ball-x-pos b) (ball-x b))then you need to deliver a contract and purpose statement, but you don't need examples, strategy, or tests.
Before you turn in your solution, make sure it passes the tests in ps03-balls-in-box-qualification.rkt. As before, download this file, save it in your set03 directory, and run it to qualify your program for grading. Be sure to commit this file to your repository so we know that you've done this correctly.
For what it's worth, my solution to this problem was 263 lines, exclusive of tests. In Fall 2013, students solved a closely related problem of comparable difficulty in a median time of 12.8 hours.
Last modified: Sat Oct 11 16:42:36 Eastern Daylight Time 2014