For people who want to sort items in hakyll by time in metadata

gistfile1.hs

sortOnM :: (Monad m, Ord k) => (a -> m k) -> [a] -> m [a]
sortOnM f xs = liftM (map fst . sortBy (comparing snd)) $
                mapM (\x -> liftM (x,) (f x)) xs

chronologicalMeta :: [Item a] -> Compiler [Item a]
chronologicalMeta = sortOnM $ getItemUTC defaultTimeLocale . itemIdentifier

recentFirstMeta :: [Item a] -> Compiler [Item a]
recentFirstMeta i = return . reverse =<< chronologicalMeta i

-- loadAllSorted :: (Binary a, Typeable a) => Pattern -> Compiler [Item a]
loadAllSorted p = loadAll p >>= recentFirstMeta