Callbacks all the way down. I blame 42% of my recent gray hair on callbacks.
let loeb x = fmap ($ loeb x) x in
loeb [ (!!5), const 3, liftM2 (+) (!!0) (!!1), (*2) . (!!2), length, const 17]
(btw, I have no idea what the hell this does. Something to do with spreadsheets, apparently. I found it on http://www.haskell.org/haskellwiki/Blow_your_mind, which has enough cleverness to make me want to cry)