This is a warm-up assignment that is intended to help you with your system setup and with breaking the ice with coding in OCaml. There are two parts: system setup then 4 simple coding problems.

System Setup

We've pre-loaded a Linux virtual machine image with all of the software you will need in this course as well as two popular text editors and development environments. Download, install, and launch the virtual machine:

1. Download and install Virtual Box for your operating system:

   https://www.virtualbox.org/wiki/Downloads

2. Download the cs1101 virtual machine image: cs1101VM. This is really huge (3GB!) file so it will take some time to download.

3. Import the virtual machine:
   1. Run VirtualBox.
   2. Select File => Import Appliance.
   3. Select Open Appliance, and choose the .ova file you just downloaded. Then select continue and then select import. This step might take some time.

4. Run the virtual machine:
   1. Select cs1101VM from the list.
   2. Click Start.

After a bit of a startup work, you should eventually see a linux desktop window adorned with camels walking on a beach. This will be your programming environment for CS1101. You'll learn to control the environment using typed commands in a command-shell.

Before we start working with the VM, lets return to the host desktop for a minute and reclaim our 3GB of our harddrive by deleting the CS1101F15.ova file that we downloaded --- we won't be needing it. You can drag it to the Trash and then delete it by emptying the trash.

Returning to the VM, select the Camel desktop. To get started, use the controls found in the lower left-hand corner of the screen to perform these tasks:

1. Launch the Chromium web browser. Navigate to the course home page for the current semester and modify the settings to make our course home page to be the default home page for the browser.

2. Open a terminal window. Type ls -l. This shows you the files in your home directory vagrant. You should see a folder named Muller1. The Muller part is my surname and the 1 part refers to the problem set number. For each problem set in this course, you'll create a folder that holds all the files that are part of your solution to the problem set. First, we'll rename the folder. The terminal window provides access to a unix command shell. Type

   > mv Muller1 YourSurname1
   

   where YourSurname is your surname. By the end of the semester, you should have YourSurname1, YourSurname2, etc., one for each problem set.

3. Open a Sublime Text window. You'll find it under Programming via the icon at the lower left:

   

   Under File and then Open navigate to the folder that you just renamed and open the file problemset1.ml.

Exiting the Virtual Machine

1. Saving the machine state

   

2. Exiting Virtual Box

Problems

val helloWorld : unit -> string
val golden : unit -> float
val hypotenuse : float -> float -> float
val yellowCircle : unit -> unit

let helloWorld () : string = failwith "Problem 1 not implemented"

Finally to some actual coding!

The four problems are specified in the problemset1.ml file. Roughly speaking, they are the following.

1. Write an OCaml function val helloWorld : unit -> string. The helloWorld function accepts no arguments and simply returns the string "Hello World!".

2. The golden ratio, aka $\phi$, is computed by $$\phi = {1 + \sqrt{5} \over 2}, $$ Write an OCaml function val golden : unit -> float that accepts no arguments and returns the golden ratio. The library function sqrt can be used in computing the result.

   # let phi = golden();;
   val phi : float = 1.618033988749895
   

3. Write an OCaml function val hypotenuse : float -> float -> float that accepts a two floating point numbers base and height giving the base and height of a right-triangle and uses the Pythagorean Theorem to return the length of the hypotenuse.

4. The function yellowCircle should use the Universe library to create picture with a large yellow circle in the display. The current definition is:

   let width = 600
   let height = width
   let radius = (float width) /. 2.
   
   let draw ignore = failwith "Problem 4 not implemented"
   
   let yellowCircle() : unit =
     big_bang ()
              ~name:"Yellow Circle"
              ~to_draw:draw
              ~width:width
              ~height:height
   

   Modify the definition to draw a yellow circle as specified. The draw function will need to use the Image.circle function from the Image Library. A quick inspection of the documentation for that function:

   val circle : float -> ?fill:bool -> ?outline_size:float -> Color.t -> t
   
   circle radius color : creates a circle of radius with color. 
   The outline width is outline_size point. Filled with color if 
   fill is true.
     

   shows that the Image.circle function requires a radius and a color. For the color, you can use Color.yellow.

   

> make

> ./problemset1

Once you have all of your functions working, exit Sublime Text. Then compress the YourSurname1 folder and upload it to the appropriate folder on the course Canvas website.