Module System.IO

Exported Datatypes

The abstract type of a handle for a stream.

Known instances:

• Eq Handle

The modes for opening a file.

Constructors:

• ReadMode :: IOMode
• WriteMode :: IOMode
• AppendMode :: IOMode

The modes for positioning with hSeek in a file.

Constructors:

• AbsoluteSeek :: SeekMode
• RelativeSeek :: SeekMode
• SeekFromEnd :: SeekMode

Exported Functions

stdin :: Handle   

Standard input stream.

Further infos:

• externally defined

stdout :: Handle   

Standard output stream.

Further infos:

• externally defined

stderr :: Handle   

Standard error stream.

Further infos:

• externally defined

openFile :: String -> IOMode -> IO Handle   

Opens a file in specified mode and returns a handle to it.

hClose :: Handle -> IO ()   

Closes a file handle and flushes the buffer in case of output file.

hFlush :: Handle -> IO ()   

Flushes the buffer associated to handle in case of output file.

hIsEOF :: Handle -> IO Bool   

Is handle at end of file?

isEOF :: IO Bool   

Is standard input at end of file?

hSeek :: Handle -> SeekMode -> Int -> IO ()   

Set the position of a handle to a seekable stream (e.g., a file). If the second argument is AbsoluteSeek, SeekFromEnd, or RelativeSeek, the position is set relative to the beginning of the file, to the end of the file, or to the current position, respectively.

hWaitForInput :: Handle -> Int -> IO Bool   

Waits until input is available on the given handle. If no input is available within t milliseconds, it returns False, otherwise it returns True.

hWaitForInputs :: [Handle] -> Int -> IO Int   

Waits until input is available on some of the given handles. If no input is available within the given milliseconds, it returns -1, otherwise it returns the index of the corresponding handle with the available data.

hReady :: Handle -> IO Bool   

Checks whether an input is available on a given handle.

hGetChar :: Handle -> IO Char   

Reads a character from an input handle and returns it. Throws an error if the end of file has been reached.

hGetLine :: Handle -> IO String   

Reads a line from an input handle and returns it. Throws an error if the end of file has been reached while reading the first character. If the end of file is reached later in the line, it ist treated as a line terminator and the (partial) line is returned.

hGetContents :: Handle -> IO String   

Reads the complete contents from an input handle and closes the input handle before returning the contents.

getContents :: IO String   

Reads the complete contents from the standard input stream until EOF.

hPutChar :: Handle -> Char -> IO ()   

Puts a character to an output handle.

hPutStr :: Handle -> String -> IO ()   

Puts a string to an output handle.

hPutStrLn :: Handle -> String -> IO ()   

Puts a string with a newline to an output handle.

hPrint :: Show a => Handle -> a -> IO ()   

Converts a term into a string and puts it to an output handle.

hIsReadable :: Handle -> IO Bool   

Is the handle readable?

hIsWritable :: Handle -> IO Bool   

Is the handle writable?

hIsTerminalDevice :: Handle -> IO Bool   

Is the handle connected to a terminal?