> I am planning to teach a "special subjects" class this coming
> fall at the University of St. Thomas entitled "Language
> Structures and Compilers".  I would like to give the students
> experience both the Ada and with compilers.  I expect that
> few, if any, of them have written a compiler, or part of same,
> before.  The proposed class-size is 15 students.

I personally teach the Compiler Theory and Design course here at the
Air Force Academy.  I tend to favor teaching concepts before tools
(see e.g. Dennis Frailey's comments in June '98 SIGCSE Bulletin).  As
a consequence, my students implement a compiler from scratch in Ada
95 that compiles a subset of Ada 95.  We use AdaGIDE/GNAT on Win 95.

> [I personally have been involved with the writing of 4 different
> compilers, two which were "real" and two of which were "toys".
> I am concerned about how big a system I can introduce the
> students to without them getting lost.]

The key thing here seems to be scaling down the language to be
compiled.  Last year, I had the students write a complete lexer for
Ada 95.  This seemed a bit of overkill, so I'll probably remove the
things we won't be using.  Our subset of Ada 95 included:

procedures/subprocedures (no packages/tasks/etc.)
simple types (integer, float -- just need two to have type checking)
array types (no records)

Important note on arrays-- it is much easier to parse array
dereferences if you use square brackets.  Is a(3,5) a function call
or an array dereference?

>    What textbook would be good?
>    What compiler(s) are available in Ada for modification?

Last year I used Crafting a Compiler in C by Fischer and LeBlanc.
The students tended to dislike it, since its examples are all in C
and they were using Ada.  This year, I got permission from the
publisher to photocopy the Ada version (Crafting a Compiler).

For our last project, I introduced them to lex/yacc (actually
scaflex/scayacc from the PAL) and we did a short exercise.

--Martin
Martin C. Carlisle, Asst Prof of Comp Sci,
US Air Force Academy, [log in to unmask]
http://www.usafa.af.mil/dfcs/bios/carlisle.html

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