Front end (part 5)

Now we fill in the quasiquotations for the makefile_item parser:

makefile_item:
  [ [ EOL -> None
    | s = WORD; "="; ws = words; EOL -> 
          Some (s, <:expr< $ws$ >>, ASSIGN)
    | t = WORD; ":"; ws = words; EOL; a = actions -> 
          let ex = <:expr<
                 let targ = $str:t$ in
                 let dep_names = $ws$ in
                 let deps = List.map resolve dep_names in
                 let actions = $a$ in
                   Mk.Rule (targ, deps, actions) >>
        in Some (t, ex, RULE) ] ];
 
actions: [ [ az = LIST0 action -> (mk_list az loc) ]  ];
action:  [ [ TAB; ws = words; EOL -> 
             <:expr< String.concat " " $ws$ >> ] ];
words:   [ [ ws = LIST0 word -> 
             (let ls = mk_list ws loc in 
              <:expr< List.flatten $ls$ >>) ] ];