Eval_zero = ->
  i = 0
  k = []
  m = 0
  n = 0

  for i in [0...MAXDIM]
    k[i] = 0

  m = 1
  n = 0
  p2 = cdr(p1)

  while (iscons(p2))
    push(car(p2))
    Eval()
    i = pop_integer()
    if (i < 1 || isNaN(i))
      # if the input is nonsensical
      # just return 0
      push(zero)
      return
    m *= i
    k[n++] = i
    p2 = cdr(p2)
  if (n == 0)
    push(zero)
    return
  p1 = alloc_tensor(m)
  p1.tensor.ndim = n
  for i in [0...n]
    p1.tensor.dim[i] = k[i]
  push(p1)