[racket] Beginning macro assignments?

I'm teaching a sophomore-level "Principles of Programming Languages" course.  We've been working through various chapters of PLAI, but I want to spent the last week or so of the semester on macros, using the "Racket Guide to Macros" at http://docs.racket-lang.org/guide/macros.html .  We'll also be talking about the C preprocessor as another example of "macros".

Does anybody have some good reasonably-easy macro-writing exercises I could assign my students?  Something that's not actually solved in the Racket Guide, but is of comparable difficulty.

For that matter, if you have good reasonably-easy exercises for the C preprocessor, that would be helpful too.


Stephen Bloch
sbloch at adelphi.edu