fn walkDir dir pattern =
(
    dirArr = GetDirectories (dir + "\\*")

    for d in dirArr do
    (
        join dirArr (getDirectories (d + "\\*"))
    )

    append dirArr (dir + "\\") -- Need to include the original top level directory

    for f in dirArr do
    (
        print (getFiles (f + pattern))
    )
)

walkDir "C:" "*.txt"