RosettaCodeData/Task/Factorial/Wortel/factorial-5.wortel

@let {
  fac &{fac n}?{
    <n 2 n
    *n !fac -n 1
  }

  ; memoized
  facM @mem &n?{
    <n 2 n
    *n !facM -n 1
  }

  [[!fac 10 !facM 10]]
}