何をやりたいか分からなくなってきたので放流する

factorialNumberSystem.fs

let rec factorial n =
    match n with
    | 0 | 1 -> 1
    | _     -> n * (factorial (n - 1))

type FactorialNumber(num: int) =
    let infactorials = Seq.initInfinite <| fun i -> factorial (i+1)
    let range = Seq.takeWhile (fun fc -> fc <= num) infactorials |> Seq.toList
    let rec factSystemize n fcs acc =
        match fcs with
        | fc::rest ->
            let quotient = n / fc
            let remainder = n % fc
            factSystemize remainder rest (quotient::acc)
        | []       -> acc
    member val Value = num with get
    member val Factorials = factSystemize num (List.rev range) [] with get
    member self.Add (other:FactorialNumber) = FactorialNumber(self.Value + other.Value)
    static member (+) (self: FactorialNumber, other: FactorialNumber) = self.Add(other)

type FactorialNumberSystemBuilder() =
    member __.Run(fn: FactorialNumber) = fn.Factorials
    member __.Return(x) = FactorialNumber(x)
    member __.Bind(x: FactorialNumber, f) = f (x.Value)

let fns = FactorialNumberSystemBuilder()

fns {
    let x = 10
    let y = 17
    return x + y
} // [1; 1; 0; 1]