In formal specifications based on abstract algebraic types and equational theory you use formulas of equational theory to specify theory. System which will satisfy those constraints is called in formal logic a model.

Modeling is process of creating a model, which abstracts of some aspects, which are unnecessary details for a specific case. So concrete system has to adhere to created model in observed aspects.

Programming is a process of creating a program which will have specific behaviour - will perform specific algorithms - and programming languages through different paradigms enable us to think in a certain specific way, which abstracts of some details, usually machine specific ones.

So could we be doing all those things at the same time, because they are principially the same? Is declarative programming the nearest attempt to do that? Could we use some sort f programming languages which will be good for programming as well as for modeling and specification?