FizzBuzz.fs

type FizzBuzz =
  FizzBuzz | Fizz | Buzz | Nat of int

let (|DivisibleBy|_|) by n =
  if n % by = 0 then Some () else None

let fizzbuzz n = match n with
  | DivisibleBy 3 & DivisibleBy 5 -> FizzBuzz
  | DivisibleBy 3 -> Fizz
  | DivisibleBy 5 -> Buzz
  | _ -> Nat n

let fizzbuzzes = Seq.initInfinite fizzbuzz

Instead of | DivisibleBy 3 & DivisibleBy 5 -> FizzBuzz
You could do | DivisibleBy 15 -> FizzBuzz

Cause if it's divisible by 3 & 5 it should be divisible by 15.