At 2001-08-09 03:53, Ashley Yakeley wrote:

-- data OpenFile = ...

openFileReadOnly :: FilePath -> IO OpenFile openFileReadWrite :: FilePath -> IO OpenFile closeFile :: OpenFile -> IO ()

fileWritable :: OpenFile -> IO Bool

fileLength :: OpenFile -> IO Integer

setFileLength :: OpenFile -> Integer -> IO () -- fill with zeros if extending

readFileBlock :: OpenFile -> Integer -> Integer -> IO [Word8] -- "readFileBlock file start length", return truncated array if past file end

writeFileBlock :: OpenFile -> Integer -> [Word8] -> IO () -- would extend file if writing past end --

Note that any number of threads could be permitted to call 'read' operations (fileLength,readFileBlock) simultaneously, but if a thread is calling a 'write' operation (setFileLength,writeFileBlock), other threads must wait on both read and write operations. It's _so_ much simpler when you don't have that pesky "file pointer" to worry about. -- Ashley Yakeley, Seattle WA