The main takeaway I got from this article is don't mix data structures and application logic. This matches my experience; complex data structures work fine if a

The main takeaway I got from this article is don't mix data structures and application logic. This matches my experience; complex data structures work fine if all the operations performed on them are in one place where they can be unit tested (or at least carefully inspected), but it works very badly if they're scattered or mixed with other things.