Trying dependent types in nim

dt.nim

type Cell[T] = ref object
  car: T
  cdr: Cell[T]

type List[T, N] = distinct Cell[T]

proc makeNil[T]: List[T, range[0..0]] = nil

proc makeCons[T, N](car: T; cdr: List[T, N]): auto =
  type N1 = range[0..high(N)+1]
  var r: Cell[T] = Cell[T](car: car, cdr: Cell[T](cdr))
  List[T, N1](r)

const theNil: List[int, range[0..0]] = makeNil[int]()
const theList1 = makeCons(1, theNil)

# % nim c dt.nim
# Hint: system [Processing]
# Hint: dt [Processing]
# dt.nim(5, 14) Hint: 'N' is declared but not used [XDeclaredButNotUsed]
# SIGSEGV: Illegal storage access. (Attempt to read from nil?)