[Haskell-cafe] Emulating bash pipe/ process lib
Marc Weber Marc Weber
marco-oweber at gmx.de
Thu Feb 9 03:25:24 EST 2006
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
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: <file descriptor: 3>: 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 ?
I've also found this library:
which seems to do something similar but is meant to pipe haskell types
between different threads (? I haven't understood what's going on there
because I can't understand Russian ;-)
Is this of any help for me?
More information about the Haskell-Cafe