I think the hard part here is using enough of a type system to ensure data sanity but not so much of one that you drown in metadata. I'm not really sure of a proper compromise like that.

Yeah, fair point. I don't know Cue well enough to know how much drowning there is, from my limited understanding you can specify as many types as you want and leave the rest dynamic, but I'm not sure at all.

That still doesn't let you comment on items in the list, or on elements of actual maps - for example if those were environment variables, now you've got a random "COMMENT" variable.

Sure, it's a hack, but it's a useful hack that works in many places.

If it doesn't error in undefined keys you cannot help people figuring out when they introduced a typo in their config