Awesome, thanks @cryogenian. I've been able to replicate the example.

In my use case, I simply need a line across the entire axis. In ECharts, I'd provide a property like xAxis: 20.0. Here's a minimal example:

https://codepen.io/saylu/pen/Zyyzgq

I tried a variant like this:

        E.markLine do
          E.lineStyle $ E.normal do
            E.solidLine
          E.buildMarkItems do
            E.addItem do
              E.symbol ET.None
              E.y 100.0

However, it seems (by looking at the generated JS) that this always expects coordinates. Is that the case?

Cheers,
Thomas

Exactly