// unclear semantics as to whether return null on null

static <A> ArrayList<A> asList(A[] a) {
  return a == null ? new ArrayList<A>() : new ArrayList<A>(Arrays.asList(a));
}

static ArrayList<Char> asList(char[] a) {
  if (a == null) null;
  ArrayList<Char> l = emptyList(a.length);
  for (i : a) l.add(i);
  ret l;
}

static ArrayList<Byte> asList(byte[] a) {
  if (a == null) null;
  ArrayList<Byte> l = emptyList(a.length);
  for (i : a) l.add(i);
  ret l;
}

static ArrayList<Integer> asList(int[] a) {
  if (a == null) null;
  ArrayList<Integer> l = emptyList(a.length);
  for (int i : a) l.add(i);
  ret l;
}

static ArrayList<Long> asList(long[] a) {
  if (a == null) null;
  ArrayList<Long> l = emptyList(a.length);
  for (long i : a) l.add(i);
  ret l;
}

static ArrayList<Float> asList(float[] a) {
  if (a == null) null;
  ArrayList<Float> l = emptyList(a.length);
  for (float i : a) l.add(i);
  ret l;
}

static ArrayList<Double> asList(double[] a) {
  if (a == null) null;
  ArrayList<Double> l = emptyList(a.length);
  for (double i : a) l.add(i);
  ret l;
}

static ArrayList<Short> asList(short[] a) {
  if (a == null) null;
  ArrayList<Short> l = emptyList(a.length);
  for (short i : a) l.add(i);
  ret l;
}

static <A> ArrayList<A> asList(Iterator<A> it) {
  new ArrayList l;
  if (it != null)
    while (it.hasNext())
      l.add(it.next());
  ret l;  
}

// disambiguation
static <A> ArrayList<A> asList(ItIt<A> s) {
  ret asList((Iterator) s);
}

static <A> ArrayList<A> asList(Iterable<A> s) {
  if (s instanceof ArrayList) return (ArrayList) s;
  ArrayList l = new ArrayList();
  if (s != null)
    for (A a : s)
      l.add(a);
  return l;
}

ifclass Producer
static <A> ArrayList<A> asList(Producer<A> p) {
  new ArrayList l;
  A a;
  if (p != null) while ((a = p.next()) != null)
    l.add(a);
  ret l;
}
endif

static <A> ArrayList<A> asList(Enumeration<A> e) {
  new ArrayList l;
  if (e != null)
    while (e.hasMoreElements())
      l.add(e.nextElement());
  return l;
}

ifclass ReverseChain
static <A> ArrayList<A> asList(ReverseChain<A> c) {
  ret c == null ? emptyList() : c.toList();
}
endif

ifclass Pair
static <A> L<A> asList(Pair<A> p) {
  ret p == null ?: ll(p.a, p.b);
}
endif