cpphs is a simplified re-implementation of cpp, the C pre-processor, in
Haskell.

This version of the C pre-processor is pretty-much feature-complete, and
compatible with the -traditional style. It has two modes:

    * conditional compilation only (--nomacro),
    * and full macro-expansion (default).

WWW: http://www.cs.york.ac.uk/fp/cpphs/