I will admit to not having written any significant functional code. However the poster child for functional programming always seems to be small programs (xmonad is the largest one I can think of, and the procedural counterparts are not that big either. Of course there is a lot of code out there that nobody can talk about). Thus I have to conclude the question of how that style scales to really large programs remains open.

That said, you didn't address my comment at all. It might be easier, but that doesn't mean it is easy to figure out what that long chain is really done - all too often the algorithm names don't tell you what you are really trying to accomplish in my experience.