Assignment 1: ISL with a touch of Class

This is assignment is to be completed and submitted individually. You may not work with anyone else.

Due: Tuesday, February 6, 11:59:59 PM EST.

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Install the Class programming language

You will need DrRacket and the Class programming language to complete this assignment. If you do not have both installed, follow the instructions included in Lab 1: Simple Data Definitions with Class.

Read the website

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1 Data Definitions and Methods in Class

For this assignment, create a single file name assign1.rkt that contains solutions for each of the following problems. (The submit server will reject your submission if it is not named appropriately.)

You may organize the file using the same order as the problems given here.

Each of these problems gives a small program designed using the design recipe of last semester. For each program, redevelop it using the class/0 language. You should use classes and methods instead in place of atomic data, structures, and functions.

1.1 Problem 1

Here is a program for modelling the state of rocket ship that launches from the bottom of the screen.

; A Rocket is positive number

; Interp: units of time that have passed since launch

; Uniform acceleration of Rocket in pixels per unit^2 of time

(define A 10)

; tick : Rocket -> Rocket

; Advance the given rocket by 1 unit of time

(check-expect (tick 5) 6)

(define (tick r)

(+ r 1))

; displacement : Rocket -> Real

; The displacement from the launch site of the given rocket

(check-expect (displacement 0) 0)

(check-expect (displacement 1) (* 1/2 A))

(check-expect (displacement 5) (* 1/2 A 25))

(define (displacement r)

(* 1/2 A (sqr r)))

1.2 Problem 2

Here is a program that deals with parts of a university fund raising system for sending letters to wealthy alumni.

; A Name is a (make-name String String)

; Interp: person's first and last name

(define-struct name (first last))

; greeting : Name -> String

; Create letter opening: "Dear <first> <last>,"

(check-expect (greeting (make-name "David" "Van Horn")) "Dear David Van Horn,")

(define (greeting n)

(string-append "Dear " (name-first n) " " (name-last n) ","))

; same-last? : Name Name -> Boolean

; Do the given names have the same last name?

(check-expect (same-last? (make-name "A" "B") (make-name "C" "B")) #true)

(check-expect (same-last? (make-name "A" "B") (make-name "A" "C")) #false)

(define (same-last? n1 n2)

(string=? (name-last n1) (name-last n2)))

1.3 Problem 3

Here is a program that deals with points in 3D space.

; A 3D is a (make-3d Real Real Real)

; Interp: a coordinate in 3D space

(define-struct 3d (x y z))

; dist3d : 3D 3D -> Real

; Compute the distance between two 3D points

(check-within (dist3d (make-3d 2 3 1) (make-3d 8 -5 0)) 10.05 0.01)

(define (dist3d p1 p2)

(sqrt (+ (sqr (- (3d-x p1) (3d-x p2)))

(sqr (- (3d-y p1) (3d-y p2)))

(sqr (- (3d-z p1) (3d-z p2))))))

1.4 Problem 4

Here is a program that deals with spheres, which relies on the program in problem 3.

; A Sphere is a (make-sphere 3D Real)

; Interp: a sphere with center and radius

(define-struct sphere (center radius))

; sphere-intersect? : Sphere Sphere -> Boolean

; Do the given spheres intersect?

(check-expect (sphere-intersect? (make-sphere (make-3d 1 1 1) 2)

(make-sphere (make-3d 2 2 1) 1))

#true)

(check-expect (sphere-intersect? (make-sphere (make-3d 1 1 1) 2)

(make-sphere (make-3d 4 4 1) 1))

#false)

(define (sphere-intersect? s1 s2)

(<= (dist3d (sphere-center s1) (sphere-center s2))

(+ (sphere-radius s1) (sphere-radius s2))))

; sphere-volume : Sphere -> Real

; Compute the volume of given sphere

(check-within (sphere-volume (make-sphere (make-3d 1 1 1) 5)) 523.6 0.1)

(define (sphere-volume s)

(* 4/3 pi (expt (sphere-radius s) 3)))

1.5 Problem 5

Here is a program that deals with shapes, which relies on the program in problem 4.

; A Shape is one of:

; - a Sphere

; - a Cube

; A Cube is a (make-cube 3D Real)

; Interp: a cube with center and side length

(define-struct cube (center side))

; cube-volume : Cube -> Real

; Compute the volume of the given cube

(check-expect (cube-volume (make-cube (make-3d 1 1 1) 5)) 125)

(define (cube-volume c)

(expt (cube-side c) 3))

; shape-volume : Shape -> Real

; Compute the volume of the given shape

(check-expect (shape-volume (make-cube (make-3d 1 1 1) 5)) 125)

(check-within (shape-volume (make-sphere (make-3d 1 1 1) 5)) 523.6 0.1)

(define (shape-volume s)

(cond [(sphere? s) (sphere-volume s)]

[(cube? s) (cube-volume s)]))

1.6 Problem 6

Here is a program that deals with arbitrarily long sequences of shapes, which relies on the program in problem 5. (It defines it own structures instead of using cons and '() to make the translation to a class/0 program more straightforward.)

; LoS (List of Shapes) is one of:

; - (make-empty-los)

; - (make-cons-los Shape LoS)

; Interp: a sequence of shapes

(define-struct empty-los ())

(define-struct cons-los (first rest))

; shapes-volume : LoS -> Real

; Compute total volume of all shapes in given list

(check-expect (shapes-volume (make-empty-los)) 0)

(check-within

(shapes-volume (make-cons-los (make-cube (make-3d 1 1 1) 5)

(make-cons-los (make-sphere (make-3d 1 1 1) 5)

(make-empty-los))))

(+ 125 523.6)

0.1)

(define (shapes-volume los)

(cond [(empty-los? los) 0]

[(cons-los? los)

(+ (shape-volume (cons-los-first los))

(shapes-volume (cons-los-rest los)))]))

Submission

Use submit.cs.umd.edu to submit your solution to the problems in part 1 as a single file called assign1.rkt.