Lambda the Ultimate

I'm working on a language (and implementation) that combines elements of relational algebra and domain algebra. For clarity, the relational algebra is about operations with relations as arguments, such as join, union and 'is subset of'. The domain algebra is about iterated tuple-level operations used to select, generate or modify relations, such as '>=', '+' and SUM().

The purpose is similar to the Functional Relational Programming described but not implemented in Out of the Tar Pit.

I have a bibliography of papers and products for some 25 or so relational languages spanning over 30 years, including the Third Manifesto and Tutorial-D, Rel, Alf, Muldis, SIRA-PRISE, BS12, Dataphor, etc. They all emphasise the relational side, and while most have a domain algebra component they do not treat it in any detail. I'm looking for more material on the domain side.

I know of one set of works directly on the subject: Aldat. I would appreciate any links or pointers for additional works in this area, preferably active now or in the recent past.