Mouse wheel with Elm

OnMouseWheel.elm

onMouseWheel : Address a -> (Float -> a) -> Attribute
onMouseWheel address toAction =
  let
    handler v = Signal.message address (toAction v)
  in
    onWithOptions "wheel" defensiveOptions decodeWheelEvent handler

defensiveOptions : Options
defensiveOptions =
    { stopPropagation = True
    , preventDefault = True
    }

decodeWheelEvent : Json.Decoder Float
decodeWheelEvent =
  oneOf
    [ at [ "deltaY" ] float
    , at [ "wheelDelta" ] float |> map (\v -> -v)
    ]
    `andThen` (\v -> if v /= 0 then succeed v else fail "Wheel of 0")