It's a guess, but I think GP uses "operational" as a synonym for "imperative". I think I encountered the term "operational semantics" in the context of Prolog programming. Denotational semantics is a term for a kind of semantics which are mathematically pure. IIRC Prolog has both operational and denotational semantics defined and they conflict. There's something about cut operator and tree pruning, but I read this long ago :-)
> It's a guess, but I think GP uses "operational" as a synonym for "imperative".
Not really. It's also possible to reason non-operationally about imperative programs, e.g., using predicate transformer semantics. It's also possible to reason operationally about non-imperative programs.
