Code Style and Testing

Refer to the below and the general "Assignment Do's and Don'ts" doc linked to on cuLearn.

- All code has been well indented and has been broken down into reasonably sized procedures (no single line should be too long; aim for about 80 characters each)

- Each procedure has been well documented (but not over-documented - don't just restate the code) with comments, including the purpose of the procedure, the expected inputs, and the expected output

- There is sufficient testing using check-expect and, at a minimum, no code is highlighted by DrRacket when the file is run.

Question 1

An accumulator is a procedure that is called repeatedly with a single numeric argument and accumulates its arguments into a sum. Each time it is called, it returns the currently accumulated sum. Write a procedure make-accumulator that generates accumulators, each maintaining an independent sum. The input to make-accumulator will correctly specify the initial value of the sum; for example

(define A (make-accumulator 5))

(A 10)

15

(A 10)

25

Question 2

Write a procedure (make-queue) that produces independent first-in-first-out queue objects, using a message-passing style.  For example:

(define queue1 (make-queue))

(define queue2 (make-queue))

Write procedures to manipulate queues. At a minimum:

1. (queue1 'empty?): boolean

2. (queue1 'enqueue! item): adds item to the queue

3. (queue1 'front): returns the next element of the queue that would be removed on dequeue

4. (queue1 'back): returns the last element of the queue that would be removed on dequeue (i.e. the most recent element added)

5. (queue1 'dequeue!): throws away the front element

6. (queue1 'print): prints some representation of the queue from front to back