[nilkn]

I've written a fair bit of Haskell, including some production software. Your second version here is my personal favorite of the variants proposed so far. It's the version I can look at and more or less instantly understand. I think sometimes folks go a little too far with using library functions to manipulate Maybe values -- not that `fromMaybe` is particularly onerous, but something about the structure of pattern matching just conveys information to my brain much faster.