Java程序辅导
C C++ Java Python Processing编程在线培训 程序编写 软件开发 视频讲解
C C++ Java Python Processing编程在线培训 程序编写 软件开发 视频讲解
Hints You cannot consider a turtle command on its own; you need to know what the turtle has already done. For example, you need to know the facing to determine the new position after evaluating Forward. We recommend defining: a data type TurtleState, which tracks the turtle’s position and facing, and a value initialState :: TurtleState, for the turtle’s initial position, facing, etc. Work through a simple [TurtleCommand] on paper, to see what your program needs to do. Break your solution apart into several functions, and test each in isolation. If you find that function is not behaving like you expect, you will have smaller units of code to debug, which is easier to get your head around. Task 3: Koch Snowflake (25 marks) The Koch Snowflake is a famous fractal (self-similar structure). The full snowflake has infinite length, which makes it hard to draw, but we can generate approximations to it using the following rules: The Koch Snowflake is made up of three sides. The approximation is parameterised by two arguments, depth and distance. An approximation to a side at depth is a straight line of length distance. An approximation to a side at depth is made up of four approximations of depth , each of which is the distance. These are arranged in a _/\_ pattern. We can draw approximations to the Koch Snowflake using our turtle system (click for larger version): 
Your Task Define a function koch :: Int -> Double -> [TurtleCommand] in src/Turtle.hs, which generates the necessary commands to draw an approximation to the Koch Snowflake. The first argument specifies the depth, and the second specifies the distance. The turtle should finish with the same position and facing as when it started. If either the depth or distance are negative, raise an error. Hints Be very clear in your mind about what happens at each level. Trace out a path for the turtle on graph paper, using the diagrammed behaviour as a guide. Actual drawing only happens at depth 1, and the other levels of the recursion position the turtle without drawing. If you get stuck, try writing out commands for one side only at depth 2, without recursion (but following the diagram closely), then look for subsequences that look like the instructions to draw a depth 1 approximation. Unit Tests (10 marks) How do you know that the program you’ve written is correct? GHC’s type checker rejects a lot of invalid programs, but you’ve written enough Haskell by now to see that a program that compiles is not necessarily correct. Testing picks up where the type system leaves off, and gives you confidence that changing one part of a program doesn’t break others. You have written simple doctests in your labs, but larger programs need more tests, so the tests you will write for this assignment will be labelled and organised in a separate file from the code. Open test/TurtleTest.hs. This file contains a number of example test cases, written using a simple test framework defined in test/Testing.hs. These files are heavily commented for your convenience. You can run the tests by executing cabal test. If it succeeds it won’t print out every test that ran, but if it fails you will see the output of the test run. If you want to see the tests every time, use cabal test --show-details=streaming instead. Your Task Replace the example tests with tests of your own. The tests that you write should show that the Haskell code you’ve written in Tasks 1-3 is working correctly. Hints General Hints Try writing tests before you write code. Then work on your code until the tests pass. Then define some more tests and repeat. This technique is called test-driven development. The expected values in your test cases should be easy to check by hand. If the tested code comes up with a different answer, then it’s clear that the problem is with the tested code and not the test case. Sometimes it is difficult to check an entire structure that’s returned from one of your functions. Maybe you can compute some feature about your result that’s easier to test? You could try computing the total distance your turtle travels, its final point after interpreting all the commands, or some other properties that are easier to reason about. If you find yourself checking something in GHCi (i.e., cabal repl comp1100-assignment2), ask yourself “should I make this into a unit test?”. The answer is often “yes”. If you are finding it difficult to come up with sensible tests, it is possible that your functions are doing too many things at once. Try breaking them apart into smaller functions and writing tests for each. Technical Hints It might be useful to define an assertion function that compares two TurtleStates against each other. The assertEqual and assertNotEqual functions will not work on the CodeWorld Picture type. If you want to write a test regarding the lines you draw on the canvas, you might have to come up with an intermediate representation for those lines. If you want to write tests about new types you have defined, add deriving (Eq, Show) to the end of the type definition, like this: data MyType = A | B | C deriving (Eq, Show) It is not possible to test for a call to error using the tools provided in this course. Style (10 marks) “[…] programs must be written for people to read, and only incidentally for machines to execute.” From the foreword to the first edition of Structure and Interpretation of Computer Programs. Programming is a brain-stretching activity, and you want to make it as easy on yourself as possible. Part of that is making sure your code is easy to read, because that frees up more of your brain to focus on the harder parts. TODO Check Link Guidance on good Haskell style can be found in this course’s Style Guide, and in lecture notes. Your Task Ensure that your code is written in good Haskell style. Technical Report (COMP1100: 15 marks) You should write a concise technical report. An excellent report will: demonstrate conceptual understanding of all major functions, and how they interact when the program as a whole runs; explain your design process, including your assumptions, and the reasons behind choices you made; discuss how you tested your program, and in particular why your tests give you confidence that your code is correct; and be well formatted without spelling or grammar errors. The maximum word count is 1000. This is a limit, not a quota; concise presentation is a virtue. Once again: This is not a required word count. They are the maximum number of words that your marker will read. If you can do it in fewer words without compromising the presentation, please do so. Your report must be in PDF format, located at the root of your assignment repository on GitLab and named Report.pdf. Otherwise, it may not be marked. The report must have a title page with the following items: Your name Your laboratory time and tutor Your university ID An excellent report will: demonstrate conceptual understanding of all major functions, and how they interact when the program as a whole runs; explain your design process, including your assumptions, and the reasons behind choices you made; discuss how you tested your program, and in particular why your tests give you confidence that your code is correct; and be well formatted without spelling or grammar errors. Content and Structure Your audience is the tutors and lecturers, who are proficient at programming and understand most concepts. Therefore you should not, for example, waste words describing the syntax of Haskell or how recursion works. After reading your technical report, the reader should thoroughly understand what problem your program is trying to solve, the reasons behind major design choices in it, as well as how it was tested. Your report should give a broad overview of your program, but focus on the specifics of what you did and why. Remember that the tutors have access to the above assignment specification, and if your report only contains details from it then you will only receive minimal marks. Below is an potential outline for the structure of your report and some things you might discuss in it. Introduction If you wish to do so you can write an introduction. In it, give: A brief overview of your program: how it works; and what it is designed to do. Content Talk about why you structured the program the way you did. Below are some questions you could answer: Program design Describe what each relevant function does conceptually. (i.e. how does it get you closer to solving the problems outlined in this assignment spec?) How do these functions piece together to make the finished program? Why did you design and implement it this way? What major design choices did you make regarding the functions that you’ve written, and the overall structure of your program? Assumptions Describe assumptions you have made about how the turtle behaves, and how this has influenced your design decisions. Testing How did you test individual functions? Be specific about this - the tutors know that you have tested your program, but they want to know how. Describe the tests that prove individual functions on their own behave as expected (i.e. testing a function with different inputs and doing a calculation by hand to check that the outputs are correct). How did you test the entire program? What tests did you perform to show that the program behaves as expected in all (even unexpected) cases? Again, be specific - did you just check that you can draw the triangles and polygons from Task 1, or did you come up with additional examples? Inspiration / external content What resources did you use when writing your program (e.g., published algorithms)? If you have used resources such as a webpage describing an algorithm, be sure to cite it properly at the end of your report in a ‘References’ section. References do not count to the maximum word limit. Reflection Discuss the reasoning behind your decisions, rather than what the decisions were. You can reflect on not only the decisions you made, but the process through which you developed the final program: Did you encounter any conceptual or technical issues? If you solved them, describe the relevant details of what happened and how you overcame them. Sometimes limitations on time or technical skills can limit how much of the assignment can be completed. If you ran into a problem that you could not solve, then your report is the perfect place to describe them. Try to include details such as: theories as to what caused the problem; suggestions of things that might have fixed it; and discussion about what you did try, and the results of these attempts. What would you have done differently if you were to do it again? What changes to the design and structure you would make if you wrote the program again from scratch? Are parts of the program confusing for the reader? You can explain them in the report (in this situation you should also make use of comments in your code). If you collaborated with others, what was the nature of the collaboration? (Note that you are only allowed to collaborate by sharing ideas, not code.) Collaborating is any discussion or work done together on planning or writing your assignment. Other info You may like to briefly discuss details of events which were relevant to your process of design - strange or interesting things that you noticed and fixed along the way. This is a list of suggestions, not requirements. You should only discuss items from this list if you have something interesting to write. Things to avoid in a technical report Line by line explanations of large portions of code. (If you want to include a specific line of code, be sure to format as described in the “Format” section below.) Pictures of code or IntelliJ. Content that is not your own, unless cited. Grammatical errors or misspellings. Proof-read it before submission. Informal language - a technical report is a professional document, and as such should avoid things such as: Unnecessary abbreviations (atm, btw, ps, and so on), emojis, and emoticons; and Stories / recounts of events not relevant to the development of the program. Irrelevant diagrams, graphs, and charts. Unnecessary elements will distract from the important content. Keep it succinct and focused. If you need additional help with report writing, the academic skills writing centre has a peer writing service and writing coaches. Format You are not required to follow any specific style guide (such as APA or Harvard). However, here are some tips which will make your report more pleasant to read, and make more sense to someone with a computer science background. Colours should be kept minimal. If you need to use colour, make sure it is absolutely necessary. If you are using graphics, make sure they are vector graphics (that stay sharp even as the reader zooms in on them). Any code, including type/function/module names or file names, that appears in your document should have a monospaced font (such as Consolas, Courier New, Lucida Console, or Monaco) Other text should be set in serif fonts (popular choices are Times, Palatino, Sabon, Minion, or Caslon). When available, automatic ligatures should be activated. Do not use underscore to highlight your text. Text should be at least 1.5 spaced. Communication Do not post your code publicly, either on Piazza or via other forums. Posts on Piazza trigger emails to all students, so if by mistake you post your code publicly, others will have access to your code and you may be held responsible for plagiarism. Once again, and we cannot stress this enough: do not post your code publicly . If you need help with your code, post it privately to the instructors. When brainstorming with your friends, do not share code. There might be pressure from your friends, but this is for both your and their benefit. Anything that smells of plagiarism will be investigated and there may be serious consequences. Sharing ideas and sketches is perfectly fine, but sharing should stop at ideas. Course staff will not look at assignment code unless it is posted privately in piazza. Course staff will typically give assistance by asking questions, directing you to relevant exercises from the labs, or definitions and examples from the lectures. Before the assignment is due, course staff will not give individual tips on writing functions for the assignment or how your code can be improved. We will help you get unstuck by asking questions and pointing you to relevant lecture and lab material. You will receive feedback on you work when marks are released. Submission Advice Start early, and aim to finish the assignment several days before the due date. At least 24 hours before the deadline, you should: Re-read the specification one final time, and make sure you’ve covered everything. Confirm that the latest version of your code has been pushed to GitLab. Ensure your program compiles and runs, including the cabal test test suite. Ensure your submission works on the lab machines. If it does not, it may fail tests used by the instructors. Proof-read and spell-check your report. Verify that your report is in PDF format, in the root of the project directory (not in src), and named Report.pdf. 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