App.fm

T App<S: Type>
| App.new(
  init: S,
  draw: S -> App.Render,
  when: App.Event -> S -> S);

T App.Render
| App.Render.txt(text: String);
| App.Render.pix(size: U32, draw: U32 -> Pair(U32,U32));

T App.Event
| App.Event.tick(date: U64, screen: Pair(U32,U32), mouse: Pair(U32,U32));
| App.Event.ukey(down: Bool, code: U16);
| App.Event.post(date: U64, auth: String, name: String, head: String, body: String);

// A demo application
App.demo.0: App(Pair(U32,U32))
  def u32
    Nat.to_u32
  def init
    Pair.new<,>(U32.0, U32.0)
  def draw(state)
    def size
      u32(256)
    def draw(i)
      case state:
      | let m_x = state.fst // mouse x
        let m_y = state.snd // mouse y
        let i_x = U32.mod(i, u32(16)) // square x
        let i_y = U32.div(i, u32(16)) // square y
        let p_x = U32.sub(U32.add(m_x, i_x), u32(8)) // pixel x
        let p_y = U32.sub(U32.add(m_y, i_y), u32(8)) // pixel y
        let p_z = u32(128) // pixel z
        let pos = U32.0
        let pos = U32.or(U32.mul(p_x, u32(1048576)), pos)
        let pos = U32.or(U32.mul(p_y, u32(256)), pos)
        let pos = U32.or(U32.mul(p_z, u32(1)), pos)
        let col = u32(4278190335) // rgba(255,0,0,255)
        Pair.new<,>(pos, col);
    App.Render.pix(size, draw)
  def when(event, state)
    case event:
    | tick => event.mouse; // sets state to mouse pos
    | ukey => state;
    | post => state;
  App.new<>(init, draw, when)