[alexisread]

Didn't https://www.odata.org/ do this already? If the Odata server understands the table relations, you can navigate through table relations in the REST query. I found that most parts of the business prefer filtering more than joining, learning another DSL other than SQL was a real barrier, and that many BI tools only support a subset of Odata, so are pretty much useless.

I definitely prefer concatenative (monadic) syntax a la Linq though, as it allows better scoping of efficient joins without a planner - it allows you to duck-tape (allusion intended) together a platform service easily.