Elm Scenes Example

scenes.elm

import Keyboard
import Mouse

mpos : Signal (Int,Int)
mpos = Mouse.position

kpos : Signal {x:Int,y:Int}
kpos = Keyboard.arrows

draw1 : (Int,Int) -> Element
draw1 (x,y) = collage 300 300
  [ rect 50 50 |> filled (blue)
  ,toForm (asText (x,y)) |> move (toFloat x - 150, toFloat -y + 150 )
  ]

draw2 : {x:Int, y:Int} -> Element
draw2 ({x,y} as k) = collage 300 300
  [ rect 50 50 |> filled (red) |> move (toFloat x * 100, toFloat y * 100)
  , toForm (asText (x,y))
  ]

scene1 : Signal Element
scene1 = draw1 <~ mpos

scene2 : Signal Element
scene2 = draw2 <~ kpos

toggle : Signal Element -> Signal Element -> Signal Bool -> Signal Element
toggle s1 s2 i =
  lift3 (,,) s1 s2 i |> lift (\(s1,s2,i) -> if i then s1 else s2)

main = toggle scene1 scene2 Mouse.isDown