Any sufficiently complicated Haskell program will contain a call to unsafePerformIO. But in all seriousness, you're quite right. Most interesting programs have

Any sufficiently complicated Haskell program will contain a call to unsafePerformIO. But in all seriousness, you're quite right. Most interesting programs have some state in them, and the top-level logic that interacts with the UI will most likely be about viewing and updating that state.