do not repeatedly evaluate second argument in for

ml.cpp

@@ -948,11 +948,11 @@ namespace builtin {
 	    for (size_t i = 0; i < list.size(); i++) {
 		    env.set(args[0].as_atom(), list[i]);
 
-		    for (size_t j = 1; j < args.size() - 1; j++)
+		    for (size_t j = 2; j < args.size() - 1; j++)
 			    args[j].eval(env);
+
 		    acc = args[args.size() - 1].eval(env);
 	    }
-
 	    return acc;
     }