Macquarie University, Department of Computing
COMP332 Programming Languages 2019 Assignment 1
Due: 11am Wednesday 4 September (week 6) Worth: 10% of unit assessment Marks breakdown:
Code: 50% (of which tests are worth 10%)
Report: 50% (of which test description is worth 10%)
Submit a notice of disruption via Ask@MQ if you are unable to submit on time for medical or other legitimate reasons.
Late penalty without proper justification: 20% of the full marks for the assessment per day, or part thereof, late.
Overview
You should consult the README file of this project What you have to do
You can clone the skeleton SBT project for this assignment from its BitBucket repository at https://bitbucket.org/dominicverity/comp332-frogs-and-toads. This skeleton contains:
1. Main.scala the driver module containing the main() entry point of the application. Also provides a utility function runAnumation() which takes a sequence of animation frames, given as an object of type Seq[doodle.image.Image] , and displays them as the frames of an animation in a window.
2. FrogsAndToads.scala this is a skeleton module in which you should put your code to solve the frogs and toads game. It currently just contains stub code for an AnimationState class and a solve() function.
3. FrogsAndToadsTests.scala this is a skeleton module in which you should put your automated tests of the functions you’ve provided in the FrogsAndToads.scala module.
Search for the FIXME comments to find places where you should put your solution code. Your task in this assignment is to:
Complete the implementation of the PuzzleState class and its associated companion object. In particular you should:
Add code to the solve() function to generate and return a solution to the frogs and
toads puzzle, expressed as a sequence of PuzzleState objects.
Add code to the animate() function to turn a solution generated by solve() into a sequence of images which can be displayed as an animation by the runAnimation() function.
Add whatever auxiliary functions / methods are necessary for your solution.
Add automated tests of the methods of the PuzzleState class, of your solve() method, and of your auxiliary functions to the FrogsAndToadsTests class in the tests module.
You should consult the comments in our code for more information about what these methods are expected to do and how they might be implemented.
In your solution you must:
1. Only use immutable values. So, for example, you should declare all of your variables as val s rather than var s.
2. You should demonstrate that you know how to use case classes and pattern matching, in particular your code should make use of the match expression.
3. Your solve() function should implement a recursive algorithm.
Plot points from Dom’s solution
Here are a few things I did in my solution. You are welcome to follow these tips in your solution or to come up with a completely new architecture for your solution.
1. I added methods called jumpFromLeft() , jumpFromRight() , slideFromLeft() and slideFromRight() to the PuzzleState class, each of which returns an object of type Option[PuzzleState] . Each one of these checks to see if the given move can be legally
executed when the game is in the PuzzleState it is called on. If that move is legal then the method returns a Some value wrapping the PuzzleState object obtained by executing that legal move, otherwise it returns None .
2. My solve() method only creates new PuzzleState objects by calling these methods on existing PuzzleState objects, in that way I know that it can only generate sequences of
PuzzleState objects that do obey the rules of the puzzle.
3. I added a toImage() method to the PuzzleState class and to each of the Cell classes, in
which I put the code to turn objects of those kinds into corresponding Image s. Maybe this requires all of those classes to implement some kind of IntoImage trait that declares the
toImage() method.
4. While I was at it I also overrode the toString methods of these classes, so that I could
easily print string representations of PuzzleState objects. This was particularly useful
when I was debugging and testing my code.
5. My code used a bunch of methods from the Option and Seq classes, including map() ,
flatMap() , getOrElse() , orElse() , zip() , and forall() . You might want to checkout what these do and use them in your own code.
A note about the Doodle library
In this assignment we are using the most recent version (9.4) of the doodle SVG library, rather than the older version (8.3) described in the Creative Scala book. We are doing this in order to be able to display our solutions as animations.
The parts of this library that involve the construction of Image objects are largely identical to the version of the library described in the book. The only difference I have noticed is that methods named things like lineWidth() and lineColor() have been renamed strokeWidth() and
strokeColor() .
Running and testing your code
The skeleton for this assignment is designed to be run from within the Scala simple build tool (SBT). To do this from the console run the command sbt from the root directory of the assignment project. After a few messages you should end up at the following prompt:
assignment1 0.1 2.12.8>
You can use the following tasks to compile, run and test the code:
run compiles and runs the application.
compile compiles any modules that have been updated since the last compile operation. test compiles any updated modules and executes the automated tests. The are simply
Scala modules which can be found in the tests directory.
console compiles any updated modules and allows you to execute Scala code at a console.
The file FrogsAndToadsTests.scala illustrates the basic infrastructure for writing automated tests using the ScalaTest framework. At the moment it contains a few very simple tests of the
PuzzleState class, that you can use as templates for your own tests. Asking questions
We’ve tried to give you lots of pointers on how to complete this assignment, but we are sure there are plenty of things we have missed. So you are strongly encouraged to ask lots questions about this assignment on the COMP332 forum. So start the assignment early and when you get stuck post a question – all of these will be answered in detail. You can, of course, ask questions about this assignment in your tutorial class, your tutor will be happy to help you.
We will not, however, answer forum questions about this assignment after 6pm on Monday the 2nd of September 2019. So please don’t leave your questions to the last moment.
What you must hand in and how
A zip file containing all of the code for your project and a type-written report.
Submit every source and build file that is needed to build your program from source, including files in the skeleton that you have not changed. Do not add any new files or include multiple versions of your files. Do not include any libraries or generated files (run the SBT clean command before you zip your project). We will compile all of the files that you submit using SBT, so you should avoid any other build mechanisms.
Your submission should include all of the tests that you have used to make sure that your program is working correctly. Note that just testing one or two simple cases is not enough for many marks. You should test as comprehensively as you can.
Your report should describe how you have achieved the goals of the assignment. Do not neglect the report since it is worth 50% of the marks for the assignment.
Your report should contain the following sections:
A title page or heading that gives the assignment details, your name and student number.
A brief introduction that summarises the aim of the assignment and the structure of the rest of the report.
A description of the design and implementation work that you have done to achieve the goals of the assignment. Listing some code fragments may be useful to illustrate your description, but don’t give a long listing. Leaving out obvious stuff is OK, as long as what you have done is clear. A good rule of thumb is to include enough detail to allow a fellow student to understand it if they are at the stage you were at when you started work on the assignment.
A description of the testing that you carried out. You should demonstrate that you have used a properly representative set of test cases to be confident that you have covered all the bases. Include details of the tests that you used and the rationale behind why they were chosen. Do not just print the tests out without explanation.
Submit your code and report electronically as a single zip file called ass1.zip using the appropriate submission link on the COMP332 iLearn website by the due date and time. Your report should be in PDF format.
DO NOT SUBMIT YOUR ASSIGNMENT OR DOCUMENTATION IN ANY OTHER FORMAT THAN ZIP and PDF, RESPECTIVELY. Use of any other format slows down the marking and may result in a mark deduction.
Marking
The assignment will be assessed according to the assessment standards for the unit learning outcomes.
Marks will be allocated equally to the code and to the report. Your code will be assessed for correctness and quality with respect to the assignment description. Marking of the report will assess the clarity and accuracy of your description and the adequacy of your testing. 20% of the marks for the assignment will be allocated to testing.
Dominic Verity
Copyright (c) 2019 by Dominic Verity. Macquarie University. All rights reserved. Last modified: 11 August 2019