import Ostap;
import Fun;
import List;

var a   = token ("a"),
      eq  = [token ("="), fun (l, _, r) {Eq (l, r)}],      
      add = [token ("+"), fun (l, _, r) {Add (l, r)}],
      sub = [token ("-"), fun (l, _, r) {Sub (l, r)}],
      mul = [token ("*"), fun (l, _, r) {Mul (l, r)}],
      div = [token ("/"), fun (l, _, r) {Div (l, r)}],      
      exp = expr ({[Nona, {eq}], [Right, {add, sub}], [Left, {mul, div}]}, a);

printf ("%s\n", parseString (exp |> bypass (eof), "a+a-a").string);
printf ("%s\n", parseString (exp |> bypass (eof), "a*a/a*a").string);
printf ("%s\n", parseString (exp |> bypass (eof), "a*a+a/a-a*a").string)