Comment by mrkeen
1 year ago
> Think of an IDE where a user is typing out code: the state is changing all the time.
That's easy mode. Mutability is often justifiable when one person is doing one thing to a computer at a time. Now extrapolate to multiple people editing the same document at once. Suddenly you're discussing CRDTs and other approaches. And now implement undo on top of that!
Likewise with git, or blockchain, or kafka. They're persistent logs so you can keep your head straight while figuring out what the current state(s) of the system can be. Even with git, when you do an in-place mutation (force-push) there's still an extra log (reflog) behind the scenes trying to keep the changes sane.
I think this is a good example of why "simple CRUD systems" are actually much more complex than people usually give them credit for. Anything seems easy if you do it badly. But multiple people editing a document at once with CRDTs and undo is still even easier than a basic CRUD application done properly: now you have multiple people editing multiple different data types at once! In such cases we should be thinking about building CRDTs over all the various operations users may be doing with the data, which means thinking about associativity and commutativity of generic data operations. Git only has to deal with merging text files line by line; CRUD applications have to deal with merging lots of different data types!