Subdirectory Walker

open System
open System.IO
open Microsoft.WindowsAPICodePack.Dialogs

let (|>>) x f = f x ; x

let DirectoryPick _ =
    let dialog = new CommonOpenFileDialog()
    dialog.IsFolderPicker <- true
    match dialog.ShowDialog() with
    | CommonFileDialogResult.Ok -> dialog.FileName
    | _ -> String.Empty

let rec getAllFiles dir =
    seq { yield! try 
                    Directory.EnumerateFiles(dir, "*.*") 
                 with 
                 | _ -> Seq.empty
          for d in (try 
                    Directory.EnumerateDirectories(dir) 
                    with 
                    | _ -> Seq.empty) do
              yield! getAllFiles d }

let DirectoryWalk path =
    try
        path
        |> getAllFiles 
        |> Seq.map ( fun x -> 
            x + "    "
            |> (fun y -> 
                try 
                    (new FileInfo(y)).Length 
                with 
                | _ -> 0L)) 
            |> Seq.reduce (+) 
            |> (fun x -> 
                (((double)x / 1024. / 1024. / 1024.) 
                |> Convert.ToString) + " GB")
    with
    | _ -> String.Empty
    

let SubdirectoryWalk path =
    Directory.GetDirectories(path)
    |> List.ofArray
    |> List.map (fun p -> 
        (25 |> (p |> DirectoryWalk).PadLeft) + "   " + p
        |> Console.WriteLine)
    |> ignore

[<STAThread>]
[<EntryPoint>]
let main argv =
    match argv.Length with
    | 0 -> DirectoryPick()
    | _ -> argv.[0]
    |> SubdirectoryWalk
    Console.ReadLine() |> ignore
    0