[worldimperator]

In the context of Finance, I have read about Haskell and other functional programming languages several times before, so I was wondering what were the specific benefits of doing financial stuff in functional languages? Is it because complex solutions are easier to prove to be correct? And how does the (more or less purely) functional approach there work out with the fact that they basically do I/O all the time, meaning (I guess) high frequency input of financial data, computing and then output from and to standardized existing interfaces?

Edit: What I mean by that is - everytime I read FP books, IO is basically what everybody tries to explain on the last few pages and is rather ashamed to do at all. That makes it hard to imagine how those languages come to use in real world scenarios, that's why I'm asking ;-)