Is is possible to construct a persistent data structure that is not referentially transparent? I suspect the answer is yes, depending on how you define side ef

Is is possible to construct a persistent data structure that is not referentially transparent? I suspect the answer is yes, depending on how you define side effects (example: a persistent array that logs operations). Which would mean "functional" is a more general adjective than "persistent" since it includes both persistence and referential transparency. Wikipedia[1] claims "There also exist persistent data structures which use destructible operations, making them impossible to implement efficiently in purely functional languages" [1] https://en.wikipedia.org/wiki/Persistent_data_structure https://en.wikipedia.org/wiki/Persistent_data_structure