Functional programming won't solve all your problems. If you insist on it, you'll just move them around on your plate.
Was recently re-reading the Unicorn Project and the main character had some wildly optimistic views about functional programming that I've heard echoed by others in real life.
Sometimes you want to model your problem space with shared state. If you're like, "nah, I only do functional stuff", you'll find yourself doing a lot of extra work ime just to do the same thing.
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