On Wed, May 09, 2007 at 10:48:15PM +0200, Mads Lindstr?m wrote: > Hi > > Look at System.Posix.IO > > I do not know if that module can do what you want. But it does deal with > FileDescriptors and handles. > > Maybe the dup function can help you. According to > http://www2.lib.uchicago.edu/~keith//tcl-course/topics/processes.html it > does: > > "The dup implements the dup system call, which duplicates one desired > open file descriptor into another. This can be used connect standard > input or standard output to a pipe. This sample code shows how a parent > process can fork the standard Unix sort command and then feed it data to > be sorted. A simple extension would allow the child to write the results > back to the parent." > > But I have not tested it yet, and I am not really familiar with Unix > inter-process communication. >
Right, good thinking. This is what I've come up with for Unix-only: > module WrapIO where > import System.IO > import System.Posix.IO > import Control.Exception > wrapIO :: IO a -> IO (a, String) > wrapIO action = do > oldStdOutput <- dup stdOutput > (rd, wr) <- createPipe > dupTo wr stdOutput > v <- action > h <- fdToHandle rd > closeFd wr > s <- hGetContents h > return (v, s) > `finally` do > dupTo oldStdOutput stdOutput > closeFd oldStdOutput Unfortunately, dupTo will not work on Win32 afaik. -- -- Matthew Danish -- user: mrd domain: cmu.edu -- OpenPGP public key: C24B6010 on keyring.debian.org _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
