Support for extensible records about slickless

[d6y]

Hello @rfuerst87 - just wanted to let you know that Dave, Miles, and I are mostly going to be tied up on work and conference preparation for a while. So just wanted to say hi 👋 and let you know we'll try to look into this, but it may be quiet for at least a couple of weeks.

[rfuerst87]

Hi @d6y, no worries. I'd be super happy if you could look into this once you have some spare time. Meanwhile I'll post my progress here (if there is any).

[d6y]

I've been (manually) seeing what a simple record might look like with slickless in a branch. Nothing much to see: https://github.com/underscoreio/slickless/compare/feature/18-records-experiments (but everything is in RecordShapeSpec.scala)

From what I recall the mappedWith code uses existing case class mapping to do the work. I guess that could be an option for records too. I think it depends on what we want the T to be in a Slick Table[T]: a record? a case class? I've been assuming working in terms of records is the way forward, but that might be a false assumption.