Small F# script demonstrating extensible FizzBuzz implementation

FizzBuzzWoof.fs

let combine fs x y = Seq.fold (fun acc f -> acc || f x y) false fs
    
let matcher f (n, msg) i =
    if f n i then
        Some msg
    else
        None
            
module Option =
    let combine op a b =
        match a,b with
        | Some x, Some y -> Some (op x y)
        | None, x | x, None -> x
        
let eval predicates hits i =
    let res =
        hits
        |> Seq.map (predicates |> combine |> matcher)
        |> Seq.map (fun f -> f i)
        |> Seq.reduce (Option.combine (+))
        
    match res with
    | Some x -> x
    | None -> sprintf "%A" i
    
let isDivisibleBy a b = b % a = 0
let rec contains a b =
    if b > 0 then
        b % 10 = a || contains (b / 10) a
    else
        false
        
let test = eval [isDivisibleBy; contains] [(3, "Fizz"); (5, "Buzz"); (7, "Woof")]

[1..100]
|> Seq.map test
|> Seq.iter (printf "%s")