Software

• We will be using DrScheme in this course. DrScheme is a development environment for Scheme code. You can download DrScheme for Unix / Linux, Windows, or Mac platforms from http://www.drscheme.org/. The software is also available on all machines in the CS labs. (If you find a computer without it, please let me know.)

  Use version 207. Some problems with printing have been reported in the labs with version 208.

• The book uses a few definitions that are not part of the Scheme standard. You can find them in this file.

• When you first run DrScheme, it will pop up a window allowing you to chose among natural languages (English, Spanish, etc.) The instructor has only used English as a natural language for interacting with DrScheme.
  When you click on "Next" in the pop-up window, it will pop up a window asking you to choose a scheme dialect. If you just click on "Finish" you will get the dialect that supports a beginning student using the textbook "How to Design Programs". That is not very useful for us! Click to expand the "PLT" menu, then click to select "Textual MzScheme (includes R5RS)", then click "Finish".
  You can change the Scheme dialect later from the "Language" menu in the DrScheme window. You can change natural language later from the "Help" menu in the DrScheme window.

• DrScheme is usually configured to have two panes in its main window. The top pane is for definitions. The bottom pane is for interactions. If you press the "Execute" button, or F5 on your keyboard, the contents of the definition window is executed. You can type tests that you don't want to turn in directly in the interaction pane.

• Debugging in DrScheme:
  • If DrScheme encounters a bug, it prints out an error message and puts up an icon of a bug in the interaction pane. Click on the bug icon to find out (approximately) how your program got to the bug.
  • DrScheme will do some simple syntax checking, mostly finding obvious spelling errors when you click the "Check Syntax" button.

    DrScheme is supposed to get more capable static checking any year now: See MrFlow.

  • DrScheme will let you single-step through a program execution. Unfortunately, this feature is currently only available in the "Beginning student" dialect of Scheme, which does not allow many of the programs that we are going to write. Use the "Language" menu of DrScheme to get to the beginning student dialect, and back.
  • You can use the test suite tool unter the File menu to create a series of tests that can be rerun when you modify your definitions.

    Recent versions of DrScheme have a facility for semi-automatic retesting. See the relevant chapter in A Brief Tour of DrScheme.

  • DrScheme is supposed to be getting a full-featured debugger "real soon now". Unfortunately the quoted words were posted in a document that referred to DrScheme version 100 and we are on version 299 now.

  • You can use a simple tracing package by typing:

    (require (lib "trace.ss"))
    

    in the interaction pane. You can then type something like

    (trace my-routine1 my-routine2)
    (myroutine-1 5)
    

    and all calls and returns from routines my-routine1 and my-routine2 will be printed along with argument and return values. Turn off by typing

    (untrace my-routine1 my-routine2)
    

    Unfortunately, to trace internal definitions, you have to invoke trace in the scope of the definition.
  • There is a tool called the "portable scheme debugger". It seems to be interfacable with the implementation of Scheme that DrScheme uses, but seems not to interface with the DrScheme development environment.

• You can get more information about DrScheme by clicking on the "Help Desk" item in the Help menu. Click on "Manuals" in the fine print under "Software". Look at the "A Brief Tour of DrScheme" manual. Look at the "PLT DrScheme Programming Environment" manual.