Seq.choose と Seq.exists で FizzBuzz

無理やりな感が満載ですが。

Seq.chooseで1から100までの数値をシーケンスのグループに分け、そのあとでSeq.existsでそれぞれのグループへの存在チェックをしています。

[<Test>]

let ``fizzbuzz with Seq.choose``() =
  let (|Fizz|_|) n = if n % 3 = 0 then Some() else None

  let (|Buzz|_|) n = if n % 5 = 0 then Some() else None
  let nums = seq { 1 .. 100 }

  let fizzbuzz = nums |> Seq.choose (fun n -> match n with Fizz & Buzz -> Some(n) | _ -> None)

  let fizz = nums |> Seq.choose (fun n -> match n with Fizz -> Some(n) | _ -> None)

  let buzz = nums |> Seq.choose (fun n -> match n with Buzz -> Some(n) | _ -> None)
  nums

  |> Seq.map (fun n -> 

                if   fizzbuzz |> Seq.exists ((=) n) then "fizzbuzz"

                elif fizz |> Seq.exists ((=) n) then "fizz"

                elif buzz |> Seq.exists ((=) n) then "buzz"

                else string(n))

  |> Seq.iter (printfn "%s")