2016 Update

Task/Run-length-encoding/Haskell/run-length-encoding-1.hs

@@ -1,4 +1,5 @@
 import Data.List (group)
+import Control.Arrow ((&&&))
 
 -- Datatypes
 type Encoded = [(Int, Char)]  -- An encoded String with form [(times, char), ...]
@@ -6,12 +7,11 @@ type Decoded = String
 
 -- Takes a decoded string and returns an encoded list of tuples
 rlencode :: Decoded -> Encoded
-rlencode = map (\g -> (length g, head g)) . group
+rlencode = map (length &&& head) . group
 
 -- Takes an encoded list of tuples and returns the associated decoded String
 rldecode :: Encoded -> Decoded
-rldecode = concatMap decodeTuple
-    where decodeTuple (n,c) = replicate n c
+rldecode = concatMap (uncurry replicate)
 
 main :: IO ()
 main = do

Task/Run-length-encoding/Haskell/run-length-encoding-2.hs

@@ -0,0 +1,13 @@
+import Data.List
+import Data.Char
+
+runLengthEncode = concatMap (\xs@(x:_) -> (show.length $ xs) ++ [x]).group
+runLengthDecode = concat.uncurry (zipWith (\[x] ns -> replicate (read ns) x))
+                 .foldr (\z (x,y) -> (y,z:x)) ([],[]).groupBy (\x y -> all isDigit [x,y])
+
+main = do
+ let text = "WWWWWWWWWWWWBWWWWWWWWWWWWBBBWWWWWWWWWWWWWWWWWWWWWWWWBWWWWWWWWWWWWWW"
+ let encode = runLengthEncode text
+ let decode = runLengthDecode encode
+ mapM_ putStrLn [text,encode,decode]
+ putStrLn $ "test: text == decode => " ++ (show $ text == decode)