Imperative code can be clean and stay clean too, it just requires more effort. Remember that functional programs are easier to understand only because they are

Imperative code can be clean and stay clean too, it just requires more effort. Remember that functional programs are easier to understand only because they are less expressive - they can't express concurrency and nondeterminism. That being said, the principle of least power applies in full force, so if (a part of) your program can be written purely functionally, it should probably be written that way.