def fruit_cost : fruit = {
  return (match fruit with
      | $Banana -> 11
      | $Apple | $Orange -> 7)
}

def amount_to_string : x is_zero_separated = {
  const ans = match x with
    | 0 ? is_zero_separated -> "Zero"
    | 0 | 1 | 2 | 3 | 4 -> "Few"
    | x ? (5..9).contains x -> "Several"
    | x ? (10..19).contains x -> "Pack"
    | _ -> "Lots"
  return ans
}