Marc Weber Marc Weber wrote:
Hi. I want to write a little haskell program executing about 4 programs passing data via pipes. As my python script seems to be slower than a bash script I want to try a ghc executable now. It should invoke different parts of a text to speech chain. This way I have one interface then.
Talar und #haskell told me that I might use runProcess and pass handles for stdin and out created by createPipe and fdToHandle.
So my simple test looks like this:
module Main where import System.IO import System.Posix.IO
main = do (fdIn,fdOut) <- createPipe let (iohIn, iohOut) = (fdToHandle fdIn, fdToHandle fdOut) hIn <- iohIn hOut <- iohOut hPutStr hIn "test" line <- hGetLine hOut print line -- should now print test having been piped through my pipe
but I get the error: pipe2:
: hPutStr: illegal operation (handle is not open for writing) And in current CVS docs in base.System.Process.hs it is said that createPipe is no longer exported ?
If you want to communicate with external programs via pipes, then System.Process should provide everything you need. Take a look at runInteractiveProcess in particular. Cheers, Simon