And what about that state that needs to exist? - like application state ( for example this text box has state in terms of keeping track of text entered, cursor

And what about that state that needs to exist? - like application state ( for example this text box has state in terms of keeping track of text entered, cursor position etc ). Where does that go? Are you creating a new immutable object at every keystroke that represents the addition of the latest event to the current state? Even then you need to store a pointer to that current state somewhere right?