Phi is a simple interpreter for a Lisp-y language, written in C99. I built it following the Build your own Lisp book. Phi primarily differs from the intepreter built in the book in that it has an explicit boolean type. I might add a few more things to Phi in the future.

1. Run make prep to create the release and debug output directories.
2. Run make release or make debug to build the build you want.