$use StdIO;

$func Gen-Perms expr = e.perms;

Gen-Perms expr =
  (/*e0*/) (expr) (/*e.perms*/) $iter {
    expr : t1 e2 =
      (e0 t1) (e2) (e.perms (t1 (<Gen-Perms e0 e2>)));
  } :: (e0) (expr) (e.perms),
  expr : /*empty*/ =
  e.perms;


$func Print-Perms (e.start) t.perm = ;

Print-Perms {
  (e.start) (t1 (v.perms)) =
    {
      v.perms : e t.p e,
        <Print-Perms (e.start t1) t.p>,
        $fail;;
    };
  (e.start) (t1 ()) = <PrintLN e.start t1>;
};


Main = {
//  <Gen-Perms '1234'> : e t.p e,
  <Gen-Perms '123456789'> :
    e ('6' (e ('5' (e ('4' (e ('3' (e ('2' (e ('1' (e.p)) e)) e)) e)) e)) e)) e,
    e.p : e t.q e,
    <Print-Perms ('654321') t.q>,
//    <WriteLN t.p>,
//    <Print-Perms () t.p>,
    $fail;;
};