Is it possible to use the eofill extension in this code ? I tried without success. Thank you.

   path carre, disque;
   carre = fullsquare scaled 200;
   disque = fullcircle scaled 200;
   draw carre numberstriped (.25,15,5) withcolor \MPcolor{magenta};
   fill disque withcolor white;
   draw carre  withcolor \MPcolor{orange};
   draw disque  withcolor \MPcolor{orange};

   path a[];
   a1 = origin -- point 3.5 of carre;
   interim ahangle := 30;
   drawdblarrow a1 withpen pencircle scaled 1.5pt withcolor darkred;
   label.top("$R$", point 1/2 of a1);