Instructions for Homework 2:

1) download and install Ocaml (http://caml.inria.fr)

2) unzip/untar the provided file imp.tgz

3) type "make" to build the executable "imp" from its sources

4) run the executable on a test program: "imp test.imp"

   This will build the ast, print it, and attempt to evaluate
   the program. 


Your task: finish up the implementation in file "eval.ml", and
submit this file in CMS. 



