FizzBuzz.fs

type IFizzBuzz =
    abstract member check : int -> bool
    abstract member getVal : unit -> string
        
type Fizz() =
    interface IFizzBuzz with
        member x.check n = (n % 3 = 0)
        member x.getVal() = "Fizz"
            
type Buzz() =
    interface IFizzBuzz with
        member x.check n = (n % 5 = 0)
        member x.getVal() = "Buzz"

type FizzBuzz(handlers : IFizzBuzz list) =
    member x.eval n =
        let result = 
            ("", handlers)
            ||> Seq.fold (fun acc h ->
                if h.check(n) then acc + h.getVal()
                else acc)
        if result = "" then string n
        else result

let fb =
    new FizzBuzz(
        [
            new Fizz()
            new Buzz()
        ])
[1..100] |> List.map(fb.eval) |> printfn "%A"