Love the elegance of F#. This code looks for the TFS Command line tool and returns Some(path) or None

FindTF

let findtfpath = 
   let VS_REGPATHS = [
                  @"Software\Wow6432Node\Microsoft\VisualStudio\10.0";
                  @"Software\Microsoft\VisualStudio\10.0";
                  @"Software\Wow6432Node\Microsoft\VisualStudio\9.0";
                  @"Software\Microsoft\VisualStudio\9.0";
                  @"Software\Wow6432Node\Microsoft\VisualStudio\8.0";
                  @"Software\Microsoft\VisualStudio\8.0"
                  ]
   let INSTALLDIR = "InstallDir";
   let TF_EXE = "TF.exe";
   let check value = match box value with 
                     | null -> None
                     | _ -> Some(value)
   VS_REGPATHS 
   |> Seq.choose (fun p -> check(Registry.LocalMachine.OpenSubKey(p)))
   |> Seq.choose (fun k -> check(k.GetValue(INSTALLDIR, null) :?> string))
   |> Seq.map (fun p -> System.IO.Path.Combine(p, TF_EXE))
   |> Seq.filter System.IO.File.Exists
   |> Seq.tryFind(fun f -> true)