I'm actually using pollen to create my online book[1] and it's been very good.

While I write my blog in markdown it's super nice to be able to mix real code with in your markup language. For example if you want to create a special layout for a specific page or if you want a table with subtly different properties than the rest, it's easy.

It's also very powerful to extend the markup itself. I added support for Tufte style sidenotes[2] which I use extensively throughout the book. This is the markup for the sidenotes:

    Lisp is a pretty nice◊sn{cult} language.

    ◊ndef["cult"]{
        Some may say it's the language to rule them all.
    }

The way it uses X-expressions to represent text is really intuitive and easy to work with. I do think there's merit to do this in lisp instead of say Python, because the modeling maps so well to lisp.

[1]: https://whycryptocurrencies.com/

[2]: https://www.jonashietala.se/blog/2019/03/04/pollen_sidenotes...