content: -- sudo apt-get install libphash0-dev
  import Data.PHash
  import Data.Maybe (fromJust, isJust)
  
  -- Applying a perceptual hash to images
  main = do
    phash1 <- imageHash "image1.jpg"
    putStrLn $ "image1: " ++ show phash1
    
    phash2 <- imageHash "image2.jpg"
    putStrLn $ "image2: " ++ show phash2
    
    phash3 <- imageHash "image3.jpg"
    putStrLn $ "image3: " ++ show phash3
  
    if isJust phash1 && isJust phash2 then do
      putStr "hamming distance between image1 and image2: "
      print $ hammingDistance (fromJust phash1) (fromJust phash2)
    else
      print "Error, could not read images"
  
    if isJust phash1 && isJust phash3 then do
      putStr "hamming distance between image1 and image3: "
      print $ hammingDistance (fromJust phash1) (fromJust phash3)
    else
      print "Error, could not read images"
  
  {-
    case (phash1, phash2) of
      (Just h1, Just h2) -> do
        putStr "hamming distance between image1 and image2: "
        print $ hammingDistance h1 h2
      _ -> putStrLn "Error, could not read images"
  
    case (phash1, phash3) of
      (Just h1, Just h3) -> do
        putStr "hamming distance between image1 and image3: "
        print $ hammingDistance h1 h3
      _ -> putStrLn "Error, could not read images"
  -}
  