let draw =
  () {
    case Dom.Canvas.fromDomElement(canvas) {
      Maybe::Just(el) =>
        {
          let start =
            {50, 20}
          let cp1 =
            {230, 30}
          let cp2 =
            {150, 80}
          let end =
            {250, 100}
          el
          |> Canvas.beginPath
          |> Canvas.moveTo(start[0], start[1])
          |> Canvas.bezierCurveTo(cp1[0], cp1[1], cp2[0], cp2[1], end[0], end[1])
          |> Canvas.stroke
          el
          |> Canvas.setFillStyle(CanvasFillStyle::String("blue"))
          |> Canvas.beginPath
          |> Canvas.arc(start[0], start[1], 5, 0, 2 * `Math.PI`)
          |> Canvas.arc(end[0], end[1], 5, 0, 2 * `Math.PI`)
          |> Canvas.fill
          el
          |> Canvas.setFillStyle(CanvasFillStyle::String("red"))
          |> Canvas.beginPath
          |> Canvas.arc(cp1[0], cp1[1], 5, 0, 2 * `Math.PI`)
          |> Canvas.arc(cp2[0], cp2[1], 5, 0, 2 * `Math.PI`)
          |> Canvas.fill
          ""
        }
      Maybe::Nothing =>
        ""
    }
  }
{
  await Timer.timeout(0)
  draw()
}
<canvas as canvas/>