Was going to say exactly this. Major common misunderstanding about even Haskell. Mutable state has to eventually be a part of basically every program that does something useful. The Haskell philosophy is more about having an explicit and predictable boundary between the pure and effectful parts of your code/system.
Though you'd be surprised at how much you can do while forgoing mutable state entirely.
Though you'd be surprised at how much you can do while forgoing mutable state entirely.