Getting Started

1  Why Clean?

Most of us are not professional programmers. In my case, I would rather go snowboarding than spend hours in front of a computer. Although people have more interesting things to do instead of studying Computer Science and Mathematics, High School counsellors force them to take Algebra courses. Therefore, everybody learns some Algebra, willing or unwilling.

Clean is a computer language that has a very neat feature, that is, all you need to program in Clean is some knowledge of Algebra, and as I told before, everybody already knows some Algebra. On the other hand, if you want to learn C++, Pascal, or LISP, you need to study a lot of new and difficult Computer Science concepts.

Clean is not the only computer language that draws its coding schemes from Mathematics. There are others: Haskell, Prolog, Mercury, etc. However, Clean is easy to install, easy to manage, and efficient, about as efficient as C. Other Mathematical languages lack at least one of these features.

Clean has one and only one drawback: Clean team members are very good in Computer Science, and used to tackling difficult problems. Therefore, the tools that they develop are very general, and tailored for experts. For instance, I found myself daunted by Clean GUI building tools. Therefore, I decided to wrap them into simpler packages before shipping.

2  Installation

It is quite easy to install Clean for Windows. Download the distribution package from
http://www.cs.ru.nl/~clean
Use an unzip tool to unpack the installation file. I suggest that you unpack the distribution file on the root of drive C, getting the following folder:
C:\Clean 2.1.0>
That is all. You can start using Clean from the DOS box, or from the Explorer. Figure 1 shows how to do it from the Explorer.

Figure 1: Starting Clean from the Explorer Window

You may want to install a shortcut to Clean on your desktop.

Figure 2: Creating a shortcut to clean

To do this, right click the mouse on the desktop, and ask for a new shortcut, as shown in figure 2. In the shortcut dialog that pops up, browse for the CleanIDE.exe (see figure 3). Finally, press Next and Finish.

Figure 3: Creating a shortcut to clean

3  Configuration and Testing

To configure the IDE, click on the Clean desktop icon. The IDE will pop up. Choose the environment submenu, and check Everything ( figure 4).

Figure 4: Checking Everything


Figure 5: Adding a new path

Let us make a small test. Choose the option File/New File from the task menu. In the New File dialog, choose a name for the file that will hold the main program. Attention: The program must have extension icl (figure 6).

Figure 6: File/New File

Use the provided text editor to type the following program:
module firststeps
import StdEnv

Start= cos(3.1416/3.0)
In the IDE text editor, the program should look as in figure 7. NB: The module must have the same name that you have chosen for the file, except for the extension. In this case, the file name is firststeps.icl. Therefore, the module name is firststeps.

In the Environment option of the main menu, check Everything. This environment will provide both a console to print the results of our programs, and a graphic user interface. Although you and I prefer a graphic user interface (GUI), let us utilize a console to test ideas and snippets.

The option File/New Project will allow you to create a project. If you have already tried your hand at C, Pascal, or OCAML, you know how difficult is to create a project in these languages. In Clean, all you need to do is to accept the option given in the New Project Dialog. The final step before compiling and running is to choose the project options. From the task menu, go to Project/Project Options, and check Show Constructors, as in figure 8. Finally, go to the option Project/Update and Run, and your program will be compiled, showing a result that is very close to sin(p/3).

Let us summarize all the steps necessary to compile a program.

Figure 7: Starting a New Project


Figure 8: Asking for a console

4  A soft introduction to GUI

I guess that ObjectIO library is something really spectacular. However, tyros often find it daunting; therefore, I wrote a wrap around it that will make your first steps somewhat easier. Download the files myIO.icl and myIO.dcl and install them. You can download zipped versions of these two libraries from the following address:
http://www.discenda.org/Clean/myio.zip
Unzip myio.zip inside C:\Clean 2.1.0\Libraries\myio\. Now, go to the Environment menu option, check Everything, and choose the Edit Current sub-option. Then, add a path to myIO, as shown in figure 5. To accomplish this step, you need to check the radio button Paths (figure 5), and press the button Append. This will put you in a browser dialog, that you can use to locate the myIO library, and add it to the path list. Do not forget to unzip the myIO.zip, so as to obtain the files myIO.dcl and myIO.icl.

4.1  Testing the GUI interface

Now, let us test the GUI interface. Check the Environment/Everything option from Clean main menu (also called task menu). Then, choose the File/NewFile option, and create a file testIO.icl. You will use the provided editor to type a Clean module into this file. The module must have the same name as the file, except for the extension:
module testIO
import StdEnv, myIO

Start world= ioDialog (RLISTtoR avg) world
Then, create a new project using the File/New File option. From the task menu, go to Project/Project Options, and check No Console. In section 3, you have chosen the Show Constructors option. This time, you must check No Console. The last step is Update and Run. Figure 9 shows the result of running the program. By the way, this program is supposed to calculate the average of a list of Real numbers.

Figure 9: guitest

You will find a summary of the steps necessary to create a GUI program below. Do not forget to download and unzip the myio library inside C:\Clean 2.1.0\Libraries\myio\, and to add a path to it through the Environment/Edit Current menu option.
This document was translated from LATEX by HEVEA.