The Functional FizzBuzz Kata

I run a coding dojo at work. For one session I'm to showing that you can use a kata to get into a new language.

I'm using the FizzBuzz Kata to to show F# (and JavaScript) because it is short. The problem is I am very new to F# and find myself devolving to objects instead of being functional.

Thus, I would like to see better ways of doing this (using nunit):

namespace FizzBuzzFSharp
    open NUnit.Framework

    module FizzBuzzer = 
        let FizzBuzz number = 
            match number with 
            | i when i % 3 = 0 && i % 5 = 0 -> "FizzBuzz"
            | i when i % 5 = 0 -> "Buzz"
            | i when i % 3 = 0 -> "Fizz"
            | _ -> number.ToString()

        []
        []
        []
        []        
        []
        []
        []
        []
        []
        []
        []
        []
        []
        []        
        []
        []        
        []
        let WhenNumber_ThenResult(number, expected) = 
            Assert.AreEqual(expected, FizzBuzz(number));

I think your implementation is fine. I might write it like this, because I find it more idiomatic in F# to avoid guards (when clauses) in pattern matching where a guard free implementation is equally concise.

let fizzbuzz x = 
    match (x % 5, x % 3) with
    | (0, 0) -> "FizzBuzz"
    | (0, _) -> "Buzz"
    | (_, 0) -> "Fizz"
    | _ -> string x

[1..100] |> List.map fizzbuzz |> List.iter (printfn "%s")

There are ways you can make this more elaborate / extensible but while that can be an interesting exercise I don't think they're really an improvement over a simple straightforward implementation like this.

StackExchange Code Review Q#64871, answer score: 4