...

• Recall that all homeworks are to should be done in pairs if possible. Each pair should submit only one copy of their assignment from the account of either partner in the pair. This directive describes how to answer both expository problems and programming problems. For detailed instructions on how to format your homework as a single (.ss) file and submit it, see the HW Checklist.

...

• Some homework problems will be conventional expository questions that require a short written answer.
• All of the assigned expository problems should be answered in the same Scheme (.ss) file as your Scheme programming exercises. Each line in the answer to an expository question should begin a "comment escape character", namely ';' as the first character on that line. Alternatively, you can enclose an entire expository problem in a Scheme box (created using the command Comment Out with a Box or in Scheme block comment brackets #| and |# (sometime called bookends). Note that you can create your entire homework file using the DrScheme editor.

...

• Most of your homework problems will be programming problems.
• The bulk Half (70%50%) of your grade on programming problems depends on good style and following the recipe (program grading is described in detail on the homework grading page). In particular, these points will be based on
  • Following 25% for following the design recipe carefully and documenting your program as you are taught in course (see below), and
  • Good 25% for good programming style as taught in the course.
• The other half of your grade will be based on demonstrated correctness:
  • 25% for passing all of our tests and 25% for construction; and
  • 25% for constructing a comprehensive set of unit tests for each function in your program.

• All assigned programming problems should be done in the same .ss file.
• At the top of your programming solution file, please put a header with the assignment number, your name and e-mail address, and your partner's name and e-mail address, like this:

  Code Block
  ;; COMP 211 HW #01 ;; Christopher Warrington <chrisw@rice.edu> ;; Gregory Malecha <gmalecha@rice.edu>

• Strictly follow the formatting and documentation directives given below under the heading Requirements. The easiest way to follow these requirements is to imitate the Sample Program solution below.

Requirements

You must include any data definitions introduced a data definition and corresponding template for each form of data processed used in your homework submissions . And the functions you write must follow the basic formsunless instructed otherwise. You only need to include a data definition and corresponding template once for an assignment, not once for every problem that uses that data defintion.

Data Definitions and Templates:

You must include any data definitions introduced in your homework submissions. You need to think devise (and document) your data design for data definitions before you start writing functions that process this data of this type. Data definitions should be documented as follows:

• Example 3. Data definition of shape:

  Code Block

  ;; A shape is either ;; * a triangle (make-triangle b h), ;; where b and h are positive-reals ;; * a square (make-square s), ;; where s is a positive-real. (define-struct triangle (base height)) (define-struct square (side)) ;; ;; Examples: ;; (make-triangle 1 2) ;; (make-triangle 2 5) ;; (make-square 4) ;; (make-square 2.5) ;; ;; Template: (enclosed in block comment brackets)for shape #| ;; shape-function : shape -> ... (define (shape-function ... shape ...) (cond [(triangle? shape) ... (triangle-base shape) ... ... (triangle-height shape) ...] [(square? shape) ... (square-side shape) ...])) |#

• Example 4. Data definition of list-of-numbers:

  Code Block

  ;; A list-of-numbers is either ;; empty, or ;; (cons n lon) ;; where n is a number, and lon is a list-of-numbers ;; ;; Examples: ;; empty ;; (cons 1 empty) ;; (cons 1 (cons 4 empty)) ;; ;; Template: (enclosed in block comment brackets)for list-of-numbers #| ;; lon-f : list-of-numbers -> ... (define (lon-f ... a-lon ...) (cond [(empty? a-lon) ...] [(cons? a-lon) ... (first a-lon) ... ... (lon-f ... (rest a-lon) ...) ... ])) |#

• Once your have written your a data definition, you can use it in the rest of the assignment.
• The template for writing a function that consumes processes a particular datatype kind of data (data type) is based only on the type corresponding data definition, and should not depend in anyway on the particular functions that you happen define on that type. In other wordsHence, there is only one template per data type. This same template is used as the starting point for writing all functions that process that data type.
• If the type is a structure, the template should have include the field extraction operations. If the type is a varietyunion, the template needs to have an appropriate cond statement (see example 3). If the type is recursive, the template tells us how the recursion should be done(includes the expected recursive calls on the recursive data components (see example 4).

Basic form of a function definition

• The basic form for each function that you write, including axillary and local functions, is as follows:
  • Example 5. Function definition for computing area of a ring:

    Code Block

    ;; area-of-ring : positive-real-number positive-real-number -> positive-real-number ;; Purpose: to compute the area of a ring whose radius is ;; outer and whose hole has a radius of inner ;; ;; Examples: ;; (area-of-ring 5 3) => 50.24 ;; (area-of-ring 5 0) => 78.5 ;; ;; Template Instantiation: (degenerate) #| (define (area-of-ring outer inner) ...) |# ;; Code: (define (area-of-ring outer inner) (- (area-of-disk outer) (area-of-disk inner))) ;; Test Examples: (check-expect (area-of-ring 5 3) 50.24) (check-expect (area-of-ring 5 0) 78.5) ... ;; Provide enough examples and tests to show you tested thoroughly

  • Example 6. Function definition for computing product of list-of-number:

    Code Block

    ;; product-of-lon : list-of-numbers -> number ;; to compute the product of numbers in a list ;; assuming product of empty list is 1 ;; Examples: ;; (product-of-lon empty) => 1 ;; (product-of-lon (cons 2 empty)) => 2 ;; (product-of-lon (cons 3 (cons 2 empty))) => 6 ;; Template instantiation #| (define (product-of-lon a-lon) (cond [(empty? a-lon) ...] [(cons? a-lon) ... (first a-lon) ... ... (product-of-lon (rest a-lon)) ... ])) |# ;; Code (define (product-of-lon a-lon) (cond [(empty? a-lon) 1] [(cons? a-lon) (* (first a-lon) (product-of-lon (rest a-lon)))])) ;; Test Examples: (check-expect (product-of-lon empty) 1) (check-expect (product-of-lon (cons 2 empty)) 2) (check-expect (product-of-lon (cons 3 (cons 2 empty))) 6) ;; Provide enough examples and tests to show you tested thoroughly

• Remember to follow the design recipe.
• It is important that things are presented in this order, so that is clear that you know the correct order for doing things.
• You are allowed to use the equal? test only for testing. You are not allowed to use it anywhere else in the code.
• If your examples get too big, then simply define a name for that big argument somewhere before you use it. You can use this name both in your comments in the example section and in the test cases in the Tests section.
• Be sure to test throughly. Corner cases and edge cases should be tested. For example, when dealing with numerical functions, 0 and 1 are often good test cases.
• When testing lists, make sure you test the following cases:
  • empty list: empty
  • list with one element: ex: (cons 3 empty)
  • list with more than one element: ex: (cons 1 (cons 3 (cons 3 (cons 7 empty))))
• Local functions cannot be tested individually, so specific tests are not required for them. However, you main function's tests need to be comprehensive enough to test the local functions.

Sample Solution to a Programming Problem

Anchor
SampleSolution SampleSolution

The following text is a good solution to the problem of sorting a list of numbers into ascending order; it pulls together all of the specific pieces of design documentation, code documentation, and testing mentioned above. It would be better if it included a few more appropriately chosen tests.

...