See the "pico" through "demi" branches for simplified versions
of Racket's macro expander.

This master branch is a placeholder for the full implementation of
Racket's macro expander. The full implementation is currently at

 Repo:         https://github.com/racket/racket7
 Subdirectory: racket/src/expander

In other words, the code is here:

 https://github.com/racket/racket7/tree/master/racket/src/expander