Studying F# : async

The sample in phosphorescence: Studying F# : Accumulator, pipe and composition is written as sync program. In this article, I try to re-write that sample to async program with async { } cluase.

Microsoft (R) F# 2.0 Interactive build 2.0.0.0
Copyright (c) Microsoft Corporation. All Rights Reserved.

> let fizzBuzzMapper data =
-     Seq.map ( fun elem -> async { return (elem, (elem % 3 = 0), (elem % 5 = 0) ) } ) data;;

val fizzBuzzMapper : seq<int> -> seq<Async<int * bool * bool>>

> let fizzBuzzReducer interims =
-     Array.foldBack (fun (elem, m3, m5) acc ->
-         match (m3, m5) with
-         | (true, true) -> "FizzBuzz" :: acc
-         | (true, false) -> "Fizz" :: acc
-         | (false, true) -> "Buzz" :: acc
-         | _ -> elem.ToString() :: acc ) interims [];;

val fizzBuzzReducer : ('a * bool * bool) [] -> string list

> [1..40] |> fizzBuzzMapper |> Async.Parallel |> Async.RunSynchronously |> fizzBuzzReducer;;
val it : string list =
  ["1"; "2"; "Fizz"; "4"; "Buzz"; "Fizz"; "7"; "8"; "Fizz"; "Buzz"; "11";
   "Fizz"; "13"; "14"; "FizzBuzz"; "16"; "17"; "Fizz"; "19"; "Buzz"; "Fizz";
   "22"; "23"; "Fizz"; "Buzz"; "26"; "Fizz"; "28"; "29"; "FizzBuzz"; "31";
   "32"; "Fizz"; "34"; "Buzz"; "Fizz"; "37"; "38"; "Fizz"; "Buzz"]
> [1..40] |> ( fizzBuzzReducer << Async.RunSynchronously << Async.Parallel << fizzBuzzMapper ) |> List.iter (fun elem -> System.Console.WriteLine(elem));;
1
2
Fizz
4
Buzz
Fizz
7
8
Fizz
Buzz
11
Fizz
13
14
FizzBuzz
16
17
Fizz
19
Buzz
Fizz
22
23
Fizz
Buzz
26
Fizz
28
29
FizzBuzz
31
32
Fizz
34
Buzz
Fizz
37
38
Fizz
Buzz
val it : unit = ()