Great to hear and that was one of my hopes! but honestly it initially came to be because i was fiddling with some jq AST-tree stuff for fq :) weirdly it was much easier to implement than i expected. Hardest part was how to handle infix operators, +/- etc, parsing without infinite recision. But once i found and managed to implement precedence climbing things got a lot easier, it's still a bit of magic to me how well it works :) the eval part had some difficulties but mostly straight forward when you can piggy-back on the "host jq", but i tried to stay away from piggy-back too much, to not piggy-back at all probably requires implement a VM somehow.

BTW your very welcome to help improve the jq documentation. Me and some other maintainers have been talking about that it probably needs an overhaul to be more approachable and also better document some nice hidden features. Join the discord if you want!