There are so many facets in object-orientedness and you can ignore many of them and still have something that's clearly object-oriented. For example, object-or

There are so many facets in object-orientedness and you can ignore many of them and still have something that's clearly object-oriented. For example, object-oriented doesn't mean you have to store all your state in objects and that objects must thus be mutable. You can, for example, return new objects of the same kind with new, modified state.