let draw =
  () {
    case Dom.Canvas.fromDomElement(canvas) {
      Maybe::Just(el) =>
        {
          // Clear canvas
          el
          |> Canvas.clearRect(0, 0, 150, 150)
          // Draw guides
          el
          |> Canvas.setStrokeStyle(CanvasFillStyle::String("#09f"))
          |> Canvas.setLineWidth(2)
          |> Canvas.strokeRect(-5, 50, 160, 50)
          // Set line styles
          el
          |> Canvas.setStrokeStyle(CanvasFillStyle::String("#000"))
          |> Canvas.setLineWidth(10)
          // Draw lines
          el
          |> Canvas.beginPath
          |> Canvas.moveTo(0, 100)
          Array.range(0, 24)
          |> Array.mapWithIndex(
            (val : Number, i : Number) {
              let dy =
                if i % 2 == 0 {
                  25
                } else {
                  -25
                }
              Canvas.lineTo(el, Math.pow(i, 1.5) * 2, 75 + dy)
              val
            })
          el
          |> Canvas.stroke
          ""
        }
      Maybe::Nothing =>
        ""
    }
  }
{
  await Timer.timeout(0)
  draw()
}
<canvas as canvas
  width="150"
  height="150"/>