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Copy your data definitions and solutions to question 2 from homework 6 to your file for homework 7. This assignment adds functions to the discussion board system from homework 6.
If you see helpers that can be used across multiple problems, define (and use) them.
As in homework 6, we will grade your tests cases as a whole sequence (question 6). We will not grade test cases for individual functions.
Write a function find-course that consumes a
course title and produces a course (structure). The produced course
should be the one from the discussion board contents with the given
title. Use this function as a helper in the remaining problems.
Write a function add-forum that consumes a
course title, a username, and a forum title and produces void. The effect
of this function is to add a new forum to the course with the given
title if the given username is a faculty member for the course. If the given
username is a student or not a member of the course, then the forum
stays unchanged. You may assume that the forum title has not been
used on another forum in the same course.
Write a function post-message that consumes a
course title, a forum title, a username, message title, and message
contents and produces void or "unknown forum". The effect of this
function is to add a new message with the given input data to the
discussion board, marked as read only by the person who posted the
message. The function should produce "unknown forum" if the forum is
not in the named course.
Write a accumulator-style function
get-unread-messages that consumes a username, a course
title and a forum title and produces a list of the messages in the
named forum that the user with the given username has not yet
read. How does the order of the output compare to that of the input?
(answer in a comment)
Write a function mark-all-read that consumes a
username, a course title, and a forum title and produces void. The
effect of the function is to mark the given username as having read
all messages that he had not read previously. You may use Scheme's
built-in function member : any-value list[] -> false OR
list[]. member returns the sublist whose first
element is the sought value or false if the value is not in the list.
> (member 2 (list 0 1 2 3)) (list 2 3) > (member 20 (list 0 1 2 3)) false
Show the sequence of test cases that you would use to test the interactions between these functions.
Turn in a single file hwk7.ss (or hwk7.scm) containing all code and documentation for this assignment. Make sure that all students' names are in a comment at the top of the file.
Refer to the Homework Expectations when preparing your solutions.
Follow the templates! We teach them to you because they help you organize your functions. Functions that don't follow the templates will lose points, so follow the templates.
Aim for reuse where possible! If a program you write for one part is useful for another part, reuse it.