Pipelining

// F#

open System.IO

let files =
    Directory.GetFiles(@"c:\", "*.*",
                       SearchOption.AllDirectories)

let totalSize =
    files
    |> Array.map (fun file -> FileInfo file)
    |> Array.map (fun info -> info.Length)
    |> Array.sum

// a snippet by Don Syme

// C#

// TODO
// implement in C#