tasks a-s

Task/Rot-13/Haskell/rot-13-1.hs

@@ -0,0 +1,7 @@
+import Data.Char
+
+rot13 :: Char -> Char
+rot13 c
+  | toLower c >= 'a' && toLower c <= 'm' = chr (ord c + 13)
+  | toLower c >= 'n' && toLower c <= 'z' = chr (ord c - 13)
+  | otherwise = c

Task/Rot-13/Haskell/rot-13-2.hs

@@ -0,0 +1,23 @@
+import System.Environment
+import System.IO
+import System.Directory
+import Control.Monad
+
+hInteract :: (String -> String) -> Handle -> Handle -> IO ()
+hInteract f hIn hOut =
+  hGetContents hIn >>= hPutStr hOut . f
+
+processByTemp :: (Handle -> Handle -> IO ()) -> String -> IO ()
+processByTemp f name = do
+  hIn <- openFile name ReadMode
+  let tmp = name ++ "$"
+  hOut <- openFile tmp WriteMode
+  f hIn hOut
+  hClose hIn
+  hClose hOut
+  removeFile name
+  renameFile tmp name
+
+process :: (Handle -> Handle -> IO ()) -> [String] -> IO ()
+process f [] = f stdin stdout
+process f ns = mapM_ (processByTemp f) ns

Task/Rot-13/Haskell/rot-13-3.hs

@@ -0,0 +1,3 @@
+main = do
+ names <- getArgs
+ process (hInteract (map rot13)) names