|Maintainer||John Goerzen <firstname.lastname@example.org>|
- hCopy :: (HVIO a, HVIO b) => a -> b -> IO ()
- hCopyProgress :: (HVIO b, HVIO c, Integral a) => b -> c -> (Maybe a -> Integer -> Bool -> IO ()) -> Int -> Maybe a -> IO Integer
- hLineCopy :: (HVIO a, HVIO b) => a -> b -> IO ()
- lineCopy :: IO ()
- copyFileLinesToFile :: FilePath -> FilePath -> IO ()
- hPutStrLns :: HVIO a => a -> [String] -> IO ()
- hGetLines :: HVIO a => a -> IO [String]
- hInteract :: (HVIO a, HVIO b) => a -> b -> (String -> String) -> IO ()
- hLineInteract :: (HVIO a, HVIO b) => a -> b -> ([String] -> [String]) -> IO ()
- lineInteract :: ([String] -> [String]) -> IO ()
- lazyMapM :: (a -> IO b) -> [a] -> IO [b]
- optimizeForBatch :: IO ()
- optimizeForInteraction :: IO ()
Entire File Handle Utilities
Opened Handle Data Copying
Copies from one handle to another in raw mode (using hGetContents).
|:: (HVIO b, HVIO c, Integral a)|
|-> (Maybe a -> Integer -> Bool -> IO ())|
Progress function -- the bool is always False unless this is the final call
|-> Maybe a|
|-> IO Integer|
Copies from one handle to another in raw mode (using hGetContents). Takes a function to provide progress updates to the user.
Copies from one handle to another in text mode (with lines).
hBlockCopy, this implementation is nice:
hLineCopy hin hout = hLineInteract hin hout id
Disk File Data Copying
Copies one filename to another in text mode.
Please note that the Unix permission bits are set at a default; you may need to adjust them after the copy yourself.
This function is implemented using
Line Processing Utilities
Given a list of strings, output a line containing each item, adding newlines as appropriate. The list is not expected to have newlines already.
Given a handle, returns a list of all the lines in that handle. Thanks to lazy evaluation, this list does not have to be read all at once.
main = do l <- hGetLines stdin hPutStrLns stdout $ filter (startswith "1") l
This is similar to the built-in
interact, but works
on any handle, not just stdin and stdout.
In other words:
interact = hInteract stdin stdout
One could view this function like this:
hLineInteract finput foutput func = let newf = unlines . func . lines in hInteract finput foutput newf
Though the actual implementation is this for efficiency:
hLineInteract finput foutput func = do lines <- hGetLines finput hPutStrLns foutput (func lines)
lineInteract = hLineInteract stdin stdout
Here's an example:
main = lineInteract (filter (startswith "1"))
This will act as a simple version of grep -- all lines that start with 1 will be displayed; all others will be ignored.
Applies a given function to every item in a list, and returns the new list. Unlike the system's mapM, items are evaluated lazily.
Sets stdin and stdout to be block-buffered. This can save a huge amount of system resources since far fewer syscalls are made, and can make programs run much faster.