You're exactly right. The problem with OO is that you are really making state changes in what you should think of as an in-memory database, but the languages of

You're exactly right. The problem with OO is that you are really making state changes in what you should think of as an in-memory database, but the languages offer you no support for doing so logically. A logical language, or as you suggest, a mixed-paradigm language, could give you some logical assistance in enforcing consistent state transitions. In OO languages, you have to enforce all the logical constraints yourself, in code. And you get so used to it, you begin to think that's the way it's done, and you embed the knowledge in your Patterns book.