Enter this code here: http://elm-lang.org/try

xonoticslideshow.elm

import Window

ith i lst = case lst of
              x::xs -> if i == 0 then x else ith (i-1) xs

images = [ "http://www.xonotic.org/m/uploads/2012/07/frontpage_007.jpg",
           "http://www.xonotic.org/m/uploads/2012/07/frontpage_021.jpg",
            "http://www.xonotic.org/m/uploads/2012/07/frontpage_008.jpg",
            "http://www.xonotic.org/m/uploads/2012/07/frontpage_005.jpg" ]

slideShow index =
  let i = index `mod` length images
  in  color black . container 500 343 middle . image 472 315 <| ith i images

tickCount = count (every (3*second))

site (w,h) e =
  collage w h
    [ toForm <| image w h "http://stats.xonotic.org/static/css/img/web_background_4.jpg",
      toForm e ]

main = lift2 site Window.dimensions (lift slideShow tickCount)