let draw =
  () {
    case Dom.Canvas.fromDomElement(canvas) {
      Maybe::Just(el) =>
        {
          // Point of transform origin
          el
          |> Canvas.arc(0, 0, 5, 0, 2 * `Math.PI`)
          |> Canvas.setFillStyle(CanvasFillStyle::String("blue"))
          |> Canvas.fill()
          // Non-rotated rectangle
          el
          |> Canvas.setFillStyle(CanvasFillStyle::String("gray"))
          |> Canvas.fillRect(100, 0, 80, 20)
          // Rotated rectangle
          el
          |> Canvas.rotate((45 * `Math.PI`) / 180)
          |> Canvas.setFillStyle(CanvasFillStyle::String("red"))
          |> Canvas.fillRect(100, 0, 80, 20)
          // Reset transformation matrix to the identity matrix
          el
          |> Canvas.setTransform(1, 0, 0, 1, 0, 0)
          ""
        }
      Maybe::Nothing =>
        ""
    }
  }
{
  await Timer.timeout(0)
  draw()
}
<canvas as canvas/>