(* The prime number sieve as a self-cloning, self-modifying object. *)

let print =
  proc(n)
    wr_putText(wr_stdout, fmt_int(n) & "\n");
  end;
  
let sieve =
  {m => 
    meth(s,n)
      print(n);
      let sieve1 = clone(s);
      s.m := 
        meth(s1,n1)
          if (n1%n) is 0 then ok else sieve1.m(n1) end
        end
    end};

for i = 2 to 100 do sieve.m(i) end;

(* Using recursion to replace cloning.
let rec newSieve =
  proc()
    {m => 
      meth(s,n)
        print(n);
        let sieve1 = newSieve();
        s.m := 
          meth(s1,n1)
            if (n1%n) is 0 then ok else sieve1.m(n1) end
          end
      end}
  end;
*)