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| System.IO | | Portability | portable | | Stability | provisional | | Maintainer | libraries@haskell.org |
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| Description |
| The standard IO library.
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| Synopsis |
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| Documentation |
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| data Handle |
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| data HandlePosn |
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| data IOMode |
| Constructors | | ReadMode | | | WriteMode | | | AppendMode | | | ReadWriteMode | |
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| data BufferMode |
| Constructors | | NoBuffering | | | LineBuffering | | | BlockBuffering (Maybe Int) | |
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| data SeekMode |
| Constructors | | AbsoluteSeek | | | RelativeSeek | | | SeekFromEnd | |
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| stdin :: Handle |
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| stdout :: Handle |
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| stderr :: Handle |
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| openFile :: FilePath -> IOMode -> IO Handle |
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| hClose :: Handle -> IO () |
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| hFileSize :: Handle -> IO Integer |
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| hIsEOF :: Handle -> IO Bool |
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| isEOF :: IO Bool |
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| hSetBuffering :: Handle -> BufferMode -> IO () |
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| hGetBuffering :: Handle -> IO BufferMode |
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| hFlush :: Handle -> IO () |
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| hGetPosn :: Handle -> IO HandlePosn |
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| hSetPosn :: HandlePosn -> IO () |
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| hSeek :: Handle -> SeekMode -> Integer -> IO () |
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| hTell :: Handle -> IO Integer |
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| hWaitForInput :: Handle -> Int -> IO Bool |
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| hReady :: Handle -> IO Bool |
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| hGetChar :: Handle -> IO Char |
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| hGetLine :: Handle -> IO String |
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| hLookAhead :: Handle -> IO Char |
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| hGetContents :: Handle -> IO String |
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| hPutChar :: Handle -> Char -> IO () |
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| hPutStr :: Handle -> String -> IO () |
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| hPutStrLn :: Handle -> String -> IO () |
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| hPrint :: (Show a) => Handle -> a -> IO () |
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| hIsOpen :: Handle -> IO Bool |
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| hIsClosed :: Handle -> IO Bool |
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| hIsReadable :: Handle -> IO Bool |
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| hIsWritable :: Handle -> IO Bool |
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| hIsSeekable :: Handle -> IO Bool |
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| isAlreadyExistsError :: IOError -> Bool |
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| isDoesNotExistError :: IOError -> Bool |
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| isAlreadyInUseError :: IOError -> Bool |
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| isFullError :: IOError -> Bool |
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| isEOFError :: IOError -> Bool |
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| isIllegalOperation :: IOError -> Bool |
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| isPermissionError :: IOError -> Bool |
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| isUserError :: IOError -> Bool |
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| ioeGetErrorString :: IOError -> String |
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| ioeGetHandle :: IOError -> Maybe Handle |
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| ioeGetFileName :: IOError -> Maybe FilePath |
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| try :: IO a -> IO (Either IOError a) |
| The construct try comp exposes IO errors which occur within a
computation, and which are not fully handled.
Other exceptions are not caught by this variant;
to catch all exceptions, use try from Control.Exception. |
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| data IO a |
A value of type IO a is a computation which, when performed,
does some I/O before returning a value of type a. There is really only one way to "perform" an I/O action: bind it to
Main.main in your program. When your program is run, the I/O will
be performed. It isn't possible to perform I/O from an arbitrary
function, unless that function is itself in the IO monad and called
at some point, directly or indirectly, from Main.main. IO is a monad, so IO actions can be combined using either the do-notation
or the >> and >>= operations from the Monad class.
| | Instances | |
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| type FilePath = String |
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| type IOError = IOException |
| The Haskell 98 type for exceptions in the IO monad.
In Haskell 98, this is an opaque type. |
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| ioError :: IOError -> IO a |
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| userError :: String -> IOError |
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| catch :: IO a -> (IOError -> IO a) -> IO a |
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| interact :: (String -> String) -> IO () |
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| putChar :: Char -> IO () |
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| putStr :: String -> IO () |
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| putStrLn :: String -> IO () |
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| print :: (Show a) => a -> IO () |
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| getChar :: IO Char |
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| getLine :: IO String |
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| getContents :: IO String |
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| readFile :: FilePath -> IO String |
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| writeFile :: FilePath -> String -> IO () |
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| appendFile :: FilePath -> String -> IO () |
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| readIO :: (Read a) => String -> IO a |
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| readLn :: (Read a) => IO a |
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| hPutBuf :: Handle -> Ptr a -> Int -> IO () |
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| hGetBuf :: Handle -> Ptr a -> Int -> IO Int |
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| fixIO :: (a -> IO a) -> IO a |
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| hSetEcho :: Handle -> Bool -> IO () |
| Set the echoing status of a handle connected to a terminal (GHC only). |
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| hGetEcho :: Handle -> IO Bool |
| Get the echoing status of a handle connected to a terminal (GHC only). |
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| hIsTerminalDevice :: Handle -> IO Bool |
| Is the handle connected to a terminal? (GHC only) |
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| Produced by Haddock version 0.4 |
