Initial data commit

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

@@ -0,0 +1,26 @@
+import Data.Char (isDigit)
+import Data.List (group, groupBy)
+
+runLengthEncode :: String -> String
+runLengthEncode =
+  concatMap
+    ( \xs@(x : _) ->
+        ( show . length $ xs
+        )
+          <> [x]
+    )
+    . group
+
+runLengthDecode :: String -> String
+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 :: IO ()
+main = do
+  let text = "WWWWWWWWWWWWBWWWWWWWWWWWWBBBWWWWWWWWWWWWWWWWWWWWWWWWBWWWWWWWWWWWWWW"
+      encode = runLengthEncode text
+      decode = runLengthDecode encode
+  mapM_ putStrLn [text, encode, decode]
+  putStrLn $ "test: text == decode => " <> show (text == decode)