sml-projects/imperative-shell/event-loop.sml

structure EventLoop =
struct
  open CML
  open InputMessage

  local
    fun loop (inputMailbox, drawMailbox, mouseX, mouseY, model) =
      let
        val inputMsg = Mailbox.recv inputMailbox
        val (model, drawMsg, mouseX, mouseY) =
          AppUpdate.update (model, mouseX, mouseY, inputMsg)
        val _ = Mailbox.send (drawMailbox, drawMsg)
      in
        loop (inputMailbox, drawMailbox, mouseX, mouseY, model)
      end
  in
    fun update (inputMailbox, drawMailbox) =
      loop (inputMailbox, drawMailbox, 0, 0, AppType.initial)
  end

  fun draw
    (drawMailbox, window, graphDrawObject, buttonDrawObject, buttonDrawLength) =
    if not (Glfw.windowShouldClose window) then
      let
        val _ = Gles3.clearColor (1.0, 1.0, 1.0, 1.0)
        val _ = Gles3.clear ()

        val _ = AppDraw.drawGraphLines graphDrawObject
        val _ = AppDraw.drawButton (buttonDrawObject, buttonDrawLength)

        val _ = Glfw.pollEvents ()
        val _ = Glfw.swapBuffers window
      in
        draw
          ( drawMailbox
          , window
          , graphDrawObject
          , buttonDrawObject
          , buttonDrawLength
          )
      end
    else
      Glfw.terminate ()
end