rotating rainbow circles

Color

import Color (..)
import Graphics.Collage (..)
import Graphics.Element (..)
import List
import Signal
import Time


main : Signal Element
main = Signal.map display angle

display : Float -> Element
display angle = collage 150 150 [rotateClockwise circles angle]

angle : Signal Float
angle = Signal.foldp (\_ angle -> angle + 1) 0 (Time.every (10 * Time.millisecond))

rotateClockwise : Form -> Float -> Form
rotateClockwise form angle = rotate ((negate << degrees) angle) form

circles : Form
circles = List.map shape [0..11]
          |> group

shape : Int -> Form
shape n =
  let angle = degrees (30 * toFloat n)
  in
      circle 10
        |> filled (hsl angle 0.7 0.5)
        |> move (45 * cos angle, 45 * sin angle)