Semantic Model (part 2)

Assume for the moment that we have a technique for
synthesizing any Ocaml program we like, given a
Makefile as input. 

We will get to that technique later.

For now, we're going to focus on building a semantic
model of a Makefile by embedding it in an Ocaml program.

By performing this embedding, we will get a lot of 
semantic analysis from the Ocaml compiler for free 	
Variable binding
Rich native datatypes (lists, strings, etc.)
Functions
Lexical environments
Type inference and type checking