let draw =
  () {
    case Dom.Canvas.fromDomElement(canvas) {
      Maybe::Just(canvasEl) =>
        case image {
          Maybe::Just(imageEl) =>
            {
              let imageSource =
                CanvasImageSource.fromImage(imageEl)
              let pattern =
                Canvas.createPattern(canvasEl, imageSource, CanvasPatternRepeat::Repeat)
              Dom.setStyle(imageEl, "display", "none")
              case pattern {
                Maybe::Just(p) =>
                  {
                    canvasEl
                    |> Canvas.setFillStyle(CanvasFillStyle::Pattern(p))
                    |> Canvas.fillRect(0, 0, 300, 300)
                    ""
                  }
                Maybe::Nothing =>
                  ""
              }
              ""
            }
          Maybe::Nothing =>
            ""
        }
      Maybe::Nothing =>
        ""
    }
  }
<>
  <img as image
    src={@asset(../../assets/canvas_createpattern.png)}
    onLoad={draw}/>
  <canvas as canvas
    width="300"
    height="300"/>
</>