Com S 342 --- Principles of Programming Languages

	   EXERCISE 04: RECURSION AND FOLLOWING THE GRAMMAR
                 (File $Date: 2005/02/07 22:14:53 $)

The purpose of this exercise is to have you learn about how to follow
a grammar when writing recursive programs.

As with all exercises, this is to be done individually.  And it is due
the day this topic is planned to be discussed in class, unless
specified otherwise (see the syllabus at:
http://www.cs.iastate.edu/~cs342/syllabus.shtml).

We expect this to help you think about the readings (see below).
If you don't have an answer or an answer that you think is good,
write down what you read, and a question or two that would have helped
you make progress.   Then you can ask that question in class;
there will be other people with the same problem, and everyone can
learn by discussing these issues.  And you'll most likely see similar
things on the homework, so it's best to understand them now.


READINGS:
Read through the end of section 5.2 of "Following the Grammar" which
is available from the course resources web page and also directly at:

   http://www.cs.iastate.edu/~cs342/docs/follow-grammar.pdf

1. [total-width]

Look at exercise in section 5.2.3 of "Following the Grammar" which is available
from the course resources web page and also directly at:

   http://www.cs.iastate.edu/~cs342/docs/follow-grammar.pdf

For this problem we just want you to write out (on the computer) an
outline for a set of procedures that follows the "window layout"
grammar.  You don't have to get your procedures to work, just write
out the defines for the procedures needed, code to choose between any
cases, and code to call the other procedures in your outline.

Make a printout of this outline.

WHAT TO HAND IN

You should have at the beginning of class, written answers for the
above questions (or written out questions and problems you encountered
for each part).  Make sure your name is on these.  Attach the
printouts, if any, requested above.

IF YOU HAVE MORE TIME

You can solve the problem completely.  If you wish, you can also test
your solution using:

   (test-ex "total-width")

ADDITIONAL READINGS

If you have time, read sections 1.1-1.2 of "Essentials of Programming
Languages" (2nd ed., 2001), by Friedman, Wand, and Haynes.