gistfile1.txt

additive <- multitive "+" additive / multitive;
multitive <- primary "*" multitive / primary;
primary <- "(" additive ")" / decimal;
decimal <- [0-9];

gistfile2.hrl

[[],
 [{head,[[97,"dditive"],
         " ","<-"," ",
         [{head,[{head,[[],[109,"ultitive"]]},
                 {tail,[[" ",[[],["\"",{string,[[[],43]]},"\""]]],
                        [" ",[[],[97,"dditive"]]]]}]},
          {tail,[[" ","/"," ",[109,"ultitive"]]]}],
         [],";"]},
  {tail,[["\n",
          [[109,"iveitive"],
           " ","<-"," ",
           [{head,[{head,[[],[112,"rimary"]]},
                   {tail,[[" ",[[],["\"",{string,...},[...]]]],
                          [" ",[[],[109,[...]]]]]}]},
            {tail,[[" ","/"," ",[112,"rimary"]]]}],
           [],";"]],
         ["\n",
          [[112,"yimary"],
           " ","<-"," ",
           [{head,[{head,[[],["\"",{string,[[[]|...]]},"\""]]},
                   {tail,[[" ",[[],[97,[...]]]],[" ",[[],[[...]|...]]]]}]},
            {tail,[[" ","/"," ",[100,"ecimal"]]]}],
           [],";"]],
         ["\n",
          [[100,"lcimal"],
           " ","<-"," ",
           ["[",
            {characters,[[[],[[],48]],[[],[[],45]],[[],[[],57]]]},
            "]"],
           [],";"]]]}],
 []]