The purpose of BufferedIO is to provide a common interface for I/O
devices that can read and write data through a buffer. Devices that
implement BufferedIO include ordinary files, memory-mapped files,
and bytestrings. The underlying device implementing a System.IO.Handle
must provide BufferedIO.
Methods
newBuffer :: dev -> BufferState -> IO (Buffer Word8)allocate a new buffer. The size of the buffer is at the discretion of the device; e.g. for a memory-mapped file the buffer will probably cover the entire file.
fillReadBuffer :: dev -> Buffer Word8 -> IO (Int, Buffer Word8)reads bytes into the buffer, blocking if there are no bytes available. Returns the number of bytes read (zero indicates end-of-file), and the new buffer.
fillReadBuffer0 :: dev -> Buffer Word8 -> IO (Maybe Int, Buffer Word8)reads bytes into the buffer without blocking. Returns the number of bytes read (Nothing indicates end-of-file), and the new buffer.
emptyWriteBuffer :: dev -> Buffer Word8 -> IO (Buffer Word8)Prepares an empty write buffer. This lets the device decide how to set up a write buffer: the buffer may need to point to a specific location in memory, for example. This is typically used by the client when switching from reading to writing on a buffered read/write device.
There is no corresponding operation for read buffers, because before reading the client will always call fillReadBuffer.
flushWriteBuffer :: dev -> Buffer Word8 -> IO (Buffer Word8)Flush all the data from the supplied write buffer out to the device. The returned buffer should be empty, and ready for writing.
flushWriteBuffer0 :: dev -> Buffer Word8 -> IO (Int, Buffer Word8)Flush data from the supplied write buffer out to the device without blocking. Returns the number of bytes written and the remaining buffer.
Instances1BufferedIO
BufferedIO FDDefined in ghc-internal-9.1003.0 · GHC.Internal.IO.FD