code for hw8ex4 of edx fp101 course

haskell/functional-programming-101-edx/interactive_programs/ex4.hs

@@ -0,0 +1,30 @@
+putStr' :: String -> IO ()
+putStr' [] = return ()
+putStr' (x : xs) = putChar x >> putStr' xs
+
+putStrLn' :: String -> IO ()
+putStrLn' [] = putChar '\n'
+putStrLn' xs = putStr' xs >> putStrLn' ""
+
+getLine' = getc []
+getc :: String -> IO String
+getc xs = do x <- getChar
+             case x of
+                '\n' -> return xs
+                _ -> getc (xs ++ [x])
+
+interact'a :: (String -> String) -> IO ()
+interact'a f = do input <- getLine'
+                  putStrLn' (f input)
+
+interact'b :: (String -> String) -> IO ()
+interact'b f = do input <- getLine'
+                  putStrLn' input
+
+-- interact'c :: (String -> String) -> IO ()
+-- interact'c f = do input <- getChar
+--                   putStrLn' (f input)
+
+interact'd :: (String -> String) -> IO ()
+interact'd f = do input <- getLine'
+                  putStr' (f input)