hw10.hs

import System.IO
--1
putStr' :: String -> IO ()
putStr' xs = sequence_ [putChar x | x <- xs]

--4
adder :: IO ()
adder = do putStr "How many numbers?"
           count <- getLine
           total <- getTotal 0 (read count :: Int)
           putStr "The total is "
           putStrLn (show total)

getTotal :: Int -> Int -> IO Int
getTotal total 0 = return total
getTotal total attempt = do n <- getLine
                            getTotal (total + (read n :: Int)) (attempt - 1)


--5
adder' :: IO ()
adder' =  do putStr "How many numbers?"
             count <- getLine
             total <- getTotal' (read count :: Int)
             putStr "The total is "
             putStrLn (show ((sum . map (\x -> read x :: Int)) total))

getTotal' :: Int -> IO [String]
getTotal' n = sequence [getLine | _ <- [1..n]]


--6
getCh :: IO Char
getCh = do  hSetEcho stdin False
            x <- getChar
            hSetEcho stdin True
            return x

delChar :: IO ()
delChar = do putChar '\b'
             putChar ' '
             putChar '\b'

getLine' :: IO String
getLine' = getLineAux []
getLineAux :: String -> IO String
getLineAux xs = do ch <- getCh
                   case ch of 
                     '\n' -> do putChar '\n'
                                return xs
                     '\DEL' -> do delChar 
                                  getLineAux (init xs)  
                     _ -> do putChar ch
                             getLineAux (xs ++ [ch])