allow different sortings

elm/Stream.elm

                 span [] [text "Written ", viewDate post.created]
                ]
main = div [] (List.map viewPost posts)
flipOrder : Order -> Order
flipOrder o = case o of
                LT -> GT
                EQ -> EQ
                GT -> LT
flipCompare : (a -> a -> Order) -> a -> a -> Order
flipCompare compare' a b = flipOrder <| compare' a b
compareBy : (a -> comparable) -> a -> a -> Order
compareBy f a b = compare (f a) (f b)
sortByDate = List.sortBy (.created >> Date.toTime)
sortByDateReverse = List.sortWith (flipCompare <| compareBy (.created >> Date.toTime))
main = div [] (List.map viewPost (sortByDateReverse posts))