[Nickle] Funny situation

[Bart Massey]

What am I doing wrong here?  Or is this a Nickle bug?
Consider this little class:

  namespace List {

      public typedef list;
      typedef union {
	  struct {
	      poly first;
	      list rest;
	  } cell;
	  void nil;
      } elem;
      public typedef &elem list;

      public list cons(poly v, list l) {
	  elem n = { cell = { first = v, rest = &l } };
	  return &n;
      }

      public poly car(list l) {
	  return l.cell.first;
      }

      public list cdr(list l) {
	  return &l.cell.rest;
      }

      public bool null(list l) {
	  union switch(l) {
	  case cell c:
	      return false;
	  case nil:
	      return true;
	  }
      }

      elem nilcell = { nil = <> };
      public list empty = &nilcell;
  }

Now if I try

  list l = empty;

I get an error: also for any variant I can think of.
Of course

  list l;
  &l = &empty;

works, but uggh.  Comments?

	Bart