CS 5510 Homework 0

Due: Tuesday, August 30th, 2011 10:45am

Part 0 – Create Handin Account

After installing cs5510-handin.plt as described in the course web page, select the Manage CS 5510 Handin... menu item from DrRacket's File menu. Change to the New User panel, and pick a username and password. (Use your real name and real Utah student ID, so that we can connect your homework submissions with you.)

You will have to install cs5510-handin.plt for DrRacket on each different filesystem that you use to get a Handin button. However, after creating a handin account once from any machine, you can use DrRacket's Handin button on any other machine.

Part 1 – Implement 42nd-power

Define the function 42nd-power, which takes a number and raises it to the 42nd power. You'll need to use the expt operator.

Your program should include test forms to check 42nd-power on a few inputs.

Example use: (42nd-power 17) should produce 4773695331839566234818968439734627784374274207965089.

Part 2 – Implement string+

Define string+ (in the same program), which takes two arguments. Each argument can be either a number or a string, and the result is always a string. Numbers should be converted to strings using number->string, and the string form of the two arguments should be appended using string-append.

Your program should include test forms to check string+ on a few inputs.

Example use: (string+ "hello" 17) should produce "hello17".

Part 3 – Implement energy-usage

Use the following type definition (add it to your program):

  (define-type Light
    [bulb (watts number?)
          (technology symbol?)]
    [candle (inches number?)])

Implement the function enery-usage, which takes a Light and produces the number of kilowatthours of electricity that the light uses in 24 hours. Your function will need to use (type-case Light ....).

As always, include relevant test forms.

Example uses: (energy-usage (bulb 100.0 'halogen)) should produce 2.4, while (energy-usage (candle 10.0)) should produce 0.

Part 4 – Implement use-for-one-hour

Implement the function use-for-one-hour, which takes a Light and produces another Light that represents the given light source after it is used for another hour. Assume that a candle burns one inch per hour (unless it is already gone), and assume that a lightbulb is the same after one hour of use.

Example uses: (use-for-one-hour (bulb 100.0 'halogen)) should produce (bulb 100.0 'halogen), while (use-for-one-hour (candle 10.0)) should produce (candle 9.0).

Part 5 – Handin

Click the Handin button in DrRacket to submit your homework. The Handin button submits whatever is in DrRacket's definitions area, so click Handin after you ave defined 42nd-power, string+, energy-usage, and use-for-one-hour, all in the same program. The submission process will check that you have defined the right names.