Hi While wrapIO works in most cases, try running this:
:m +Control.Concurrent forkIO (let foo = do threadDelay 1000000; print "A"; foo in foo) I am not saying that this makes wrapIO unusable - just that it is not bulletproof. If not using forkIO is ok, then this is a much easier solution, than creating a separate process for running "GHC as a library" - that is having the GUI in one process and having "GHC as a library in a child process. Greetings, Mads Matthew Danish wrote: > 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. > _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
