[sriku]

FD constraint programming is powerful. Mozart/Oz goes one step further by making the search strategies programmable within the language using the idea of computational spaces.

I think two of the OP's notes are covered in Mozart/Oz - concurrent programming using data floor variables (roughly equivalent to promises) and logic programming, including finite domain constraints.

[zmonx]

I agree, with only one small additional remark: In general, a programmable search strategy sacrifices termination guarantees for more generality. That's a completely defensible approach of course, and not an argument against this path of development! Still, it comes at a price, and researchers working in termination analysis may prefer precisely the tighter reins and more stringent resulting properties we obtain when we eschew programmable strategies in specific parts of the language.

For finite domain constraints, such guarantees are a major attraction in the Prolog community: If setting up the constraints terminates, then setting up the constraints plus search also terminates. That's a rather valuable and strong guarantee (since it is the search that can take take infeasibly long more often than setting up the constraints), and it breaks down if the search itself is more generally programmable.