ex.hs

chunksOf :: Int -> [a] -> [[a]]
chunksOf _ [] = []
chunksOf n l = take n l : chunksOf n (drop n l)

type Pixel = [Int]

serialize :: NP.PPM -> String
serialize (NP.PPM (NP.PPMHeader t w h) img)
    = unlines ( [show (maximum rgbList)
                , show h
                , show w
                , "P3"] ++ pixelData)
  where
    rgbList :: [Int]
    rgbList = NP.pixelDataToIntList img

    pixels :: [Pixel]
    pixels = chunksOf 3 rgbList

    pixelToAscii :: [Int] -> String
    pixelToAscii = unwords . fmap show

    rows :: [[Pixel]]
    rows = chunksOf 10 pixels

    serializeRow :: [Pixel] -> String
    serializeRow = unwords . fmap pixelToAscii

    pixelData :: [String]
    pixelData = serializeRow <$> rows