Dr. Scheme Dr. Scheme is a scheme interpreter. Scheme, of course, is the language we are learning. An interpreter translates your code into a format the computer can use. You are required to use Dr. Scheme for your homework in this course. It is available for about 10 platforms (including Windows, Mac OS, linux, and unix) so you shouldn't have a problem there. Dr. Scheme can be downloaded for free by clicking this link. Documentation is available at the same site. Once it is downloaded, you will want to launch the Dr. Scheme application (there are other executables, but this is the one you want). It offers you a tour on the first run which I suggest taking. Be advised, Dr. Scheme can take a pretty long time to load up. Don't worry about it...be patient. Within Dr. Scheme, you have the option of choosing your "language level". To make debugging easier, the software offers these levels. Unfortunately, the lower language levels (Beginning Student, etc), restrict the language and you do not have the functionality available that you will need for this course. In order for your code, and the code mentioned in the next paragraph, to work, you need to have the language level set to "Full Scheme". You can set this by going to the language menu and choosing Configure Language. Select "Full Scheme". This will pop up another window for you which asks about the language features. You will want to select the first option, "Graphical (Mr. Ed)". In addition to Dr. Scheme, Simply Scheme, our book, uses a special file to give you some built in functions. I have revised that file to work with Dr. Scheme, and it is available for download here. To use this in your application, the syntax is: (load "test.scm") As with everything in a formal programming language, you must be precise. All syntax given in class must be used exactly as it is presented. With respect to the above example, everything needs to be in lower case, and the file name you are loading needs to be in quotes. Another thing to note is that Dr. Scheme will look in it's own folder/directory to locate the test.scm file. It won't search your hard drive...so make a copy of the file and put it in the Dr. Scheme folder. To execute commands, the first of which was presented above, you can do two things. The first is to type in the top window of Dr. Scheme and click execute when you are done. The other option is to type in the bottom window and simply hit enter. Both options will work. However, it is easier to edit long code using the first method because you can make small changes and just click execute again. Any errors will show up in the bottom window. Also note that you shouldn't use both methods together. If you execute code in the top window, and then add and execute code from the bottom window (by typing and hitting enter), that will work. This is actually a very good method for testing code. However, if you make changes and re-execute the code in the top window, it forgets about everything you typed in the bottom window previously. I talk about two windows: top and bottom. To be correct, the top window is the definition window and the bottom one is the interactions window. This is important because you will need to save the contents of both. For homework, you need to turn in a copy of your code and of the code being used. The code is in the definitions window (usually), and the code being used is in the interactions window. To save definitions (very important), you simply go to the file menu and choose Save Definitions. To save the interactions window, you have to go to the file menu, select "Save Other" and then choose interactions. Note that when you are electronically turning in homework, we do not need interactions, just definitions (we will be running your code ourselves). You do need to turn in a hard copy of both the definitions and the interaction.