Subtyping in scala program | Computer Science homework help

// GENERATED

/* INSTRUCTIONS

 *

 * Complete the exercises below.  For each “EXERCISE” comment, add

 * code immediately below the comment.

 *

 * Please see README.md for instructions, including compilation and testing.

 * 

 * GRADING

 * 

 * 1. Submissions MUST compile using SBT with UNCHANGED configuration and tests with no

 *    compilation errors.  Submissions with compilation errors will receive 0 points.

 *    Note that refactoring the code will cause the tests to fail.

 *

 * 2. You MUST NOT edit the SBT configuration and tests.  Altering it in your submission will

 *    result in 0 points for this assignment.

 *

 * 3. You MUST NOT use while loops or (re)assignment to variables (you can use “val” declarations,

 *    but not “var” declarations).  You must use recursion instead.

 *

 * 4. You may declare auxiliary functions if you like.

 *

 * SUBMISSION

 *

 * 1. Push your local repository to the repository created for you on Bitbucket before the deadline.

 *

 * 2. Late submissions will not be permitted because solutions will be discussed in class.

 * 

 */

object subtyping {

  // Instances of Counter have a integer field that can be incremented, decremented, or read.

  class Counter {

    private var n = 0

    def increment () = { n = n + 1 }

    def decrement () = { n = n – 1 }

    def get () : Int = n

  }

  // EXERCISE 1: complete the following function.

  // The observeCounter function has one parameter f: a function that accepts (a reference to) a Counter instance but returns nothing.

  // The observeCounter function should call f with (a reference to) an object (of a class extending Counter).

  // Your class that extends Counter must keep track of the total number of times that increment/decrement have been called.

  // I.e., if the increment method is called 3 times on an instance, and the decrement method is called 2 times on the same instance, then it should store 5  (somewhere other than the existing field n).

  // observeCounter should call f, and then return the total number of times that increment/decrement were called on the instance by f.

  def observeCounter (f : Counter => Unit) : Int = {

val o1 = new Counter()

f(o1)

o1.get()

    // TODO: Provide definition here.

//    -1

  }

  // EXERCISE 2: complete the following function.

  // It is the same as observeCounter except that f has a parameter of type List[Counter] not Counter.

  // f will insist that the List[Counter] has length 3.

  // You must return a List[Int] not an Int.

  // The first element of the result List[Int] must correspond to the number of times that increment/decrement were called on the first element of type List[Counter], similarly for the second and third elements.

  def observeCounterList (f : List[Counter] => Unit) : List[Int] = {

    // TODO: Provide definition here.

    List (-1, -1, -1)

  }

  // EXERCISE 3: complete the following function.

  // It is the same as observeCounterList except that f has a parameter of type Array[Counter] not List[Counter].

  // f will insist that the Array[Counter] has length 3.

  // You must return a Array[Int] not a List[Int].

  // The first element of the result Array[Int] must correspond to the number of times that increment/decrement were called on the first element of type Array[Counter], similarly for the second and third elements.

  def observeCounterArray (f : Array[Counter] => Unit) : Array[Int] = {

    // TODO: Provide definition here.

    List (-1, -1, -1).toArray

  }

}

Place your order
(550 words)

Approximate price: $22

Calculate the price of your order

550 words
We'll send you the first draft for approval by September 11, 2018 at 10:52 AM
Total price:
$26
The price is based on these factors:
Academic level
Number of pages
Urgency
Basic features
  • Free title page and bibliography
  • Unlimited revisions
  • Plagiarism-free guarantee
  • Money-back guarantee
  • 24/7 support
On-demand options
  • Writer’s samples
  • Part-by-part delivery
  • Overnight delivery
  • Copies of used sources
  • Expert Proofreading
Paper format
  • 275 words per page
  • 12 pt Arial/Times New Roman
  • Double line spacing
  • Any citation style (APA, MLA, Chicago/Turabian, Harvard)

Our guarantees

Delivering a high-quality product at a reasonable price is not enough anymore.
That’s why we have developed 5 beneficial guarantees that will make your experience with our service enjoyable, easy, and safe.

Money-back guarantee

You have to be 100% sure of the quality of your product to give a money-back guarantee. This describes us perfectly. Make sure that this guarantee is totally transparent.

Read more

Zero-plagiarism guarantee

Each paper is composed from scratch, according to your instructions. It is then checked by our plagiarism-detection software. There is no gap where plagiarism could squeeze in.

Read more

Free-revision policy

Thanks to our free revisions, there is no way for you to be unsatisfied. We will work on your paper until you are completely happy with the result.

Read more

Privacy policy

Your email is safe, as we store it according to international data protection rules. Your bank details are secure, as we use only reliable payment systems.

Read more

Fair-cooperation guarantee

By sending us your money, you buy the service we provide. Check out our terms and conditions if you prefer business talks to be laid out in official language.

Read more