Back end (part 2)

Recall also that our Ocaml program will produce a single value
of the following rule type:

type file = string
type actions = string list
type rule = Rule of (file * rule list * actions)

For example:

Rule ("emacs", 
  [ Rule ("emacs.c", [], []);
    Rule ("lisp.o", 
      [ Rule ("lisp.c", [], []) ],
      [ "gcc -c lisp.c" ] );
    Rule ("buffer.h", [] []); ],
  [ "gcc -o emacs emacs.c lisp.o" ] )

Which we must translate into a C program