September 2017 Update

Task/Huffman-coding/Haskell/huffman-coding-1.hs

@@ -2,23 +2,36 @@ import Data.List
 import Control.Arrow
 import Data.Ord
 
-data HTree a = Leaf a | Branch (HTree a) (HTree a)
-                deriving (Show, Eq, Ord)
+data HTree a
+  = Leaf a
+  | Branch (HTree a)
+           (HTree a)
+  deriving (Show, Eq, Ord)
 
 test :: String -> IO ()
-test s = mapM_ (\(a,b)-> putStrLn ('\'' : a : "\' : " ++ b))
-         . serialize . huffmanTree . freq $ s
+test =
+  mapM_ (\(a, b) -> putStrLn ('\'' : a : "\' : " ++ b)) .
+  serialize . huffmanTree . freq
 
 serialize :: HTree a -> [(a, String)]
-serialize (Branch l r) = map (second('0':)) (serialize l) ++ map (second('1':)) (serialize r)
-serialize (Leaf x)     = [(x, "")]
+serialize (Branch l r) =
+  (second ('0' :) <$> serialize l) ++ (second ('1' :) <$> serialize r)
+serialize (Leaf x) = [(x, "")]
 
-huffmanTree :: (Ord w, Num w) => [(w, a)] -> HTree a
-huffmanTree = snd . head . until (null.tail) hstep
-                  . sortBy (comparing fst) . map (second Leaf)
+huffmanTree
+  :: (Ord w, Num w)
+  => [(w, a)] -> HTree a
+huffmanTree =
+  snd .
+  head . until (null . tail) hstep . sortBy (comparing fst) . (second Leaf <$>)
 
-hstep :: (Ord a, Num a) => [(a, HTree b)] -> [(a, HTree b)]
-hstep ((w1,t1):(w2,t2):wts) = insertBy (comparing fst) (w1 + w2, Branch t1 t2) wts
+hstep
+  :: (Ord a, Num a)
+  => [(a, HTree b)] -> [(a, HTree b)]
+hstep ((w1, t1):(w2, t2):wts) =
+  insertBy (comparing fst) (w1 + w2, Branch t1 t2) wts
 
-freq :: Ord a => [a] -> [(Int, a)]
-freq = map (length &&& head) . group . sort
+freq
+  :: Ord a
+  => [a] -> [(Int, a)]
+freq = ((length &&& head) <$>) . group . sort