It'd be especially nice if database schemas mapped to F# types more readily. JSON db's kinda do it, but with no defined schema and no joins. It seems like it'd be not terribly difficult to augment regular SQL databases with something akin to the F# type system to define table schemas, rather than just flat data in columns. Then "SQL" could be extended to include `match` expressions.
I've taken the approach of converting my models to XML, mostly because they map 1:1 from F#-land to XML-land, and I can use SQL Server's XML Indices, but most importantly, I can use XSLT to evolve my persisted models upon change change to F# code.
Then using a bit of F# Quotations, I can convert most match queries to XPath queries and query SQL Server directly (still work-in-progress).
But running into performance problems, so it's not 100% done.
Yeah, I did the first part a couple years ago too. I also put the whole thing behind a VCS so we'd have version-controlled data. But, yeah, it didn't scale well enough and I ended up dropping that for mongodb, and later for postgres.