[Haskell-cafe] No handles from createProcess
Henk-Jan van Tuyl
hjgtuyl at chello.nl
Mon Dec 15 14:11:36 UTC 2014
L.S.,
I am experimenting with the createProcess function from the package
"process"; this function does not return any handle, on both Ubuntu and
Windows. I am doing something wrong, or is this a bug? (I am using GHC
7.8.3 on both platforms.)
The program I am running:
---✂----------------------------------------------
import System.IO
import System.Process
f =
do
( maybeStdinHandel
, maybeStdoutHandel
, maybeStderrHandel
, processHandle
) <- createProcess (proc "cat" ["a.txt"])
case maybeStdinHandel of
Just stdinHandel ->
do
putStrLn "stdin"
_ -> putStrLn "No stdin handle"
case maybeStdoutHandel of
Just stdoutHandel ->
do
putStrLn "stdout"
putStrLn =<< hGetContents stdoutHandel
_ -> putStrLn "No stdout handle"
case maybeStderrHandel of
Just stderrHandel ->
do
putStrLn "stderr"
putStrLn =<< hGetContents stderrHandel
_ -> putStrLn "No stderr handle"
main = f
---✂----------------------------------------------
The output:
---✂----------------------------------------------
$ ./ProcessTry
No stdin handle
No stdout handle
No stderr handle
asdf
---✂----------------------------------------------
(asdf is the contents of file a.txt)
Regards,
Henk-Jan van Tuyl
--
Folding at home
What if you could share your unused computer power to help find a cure? In
just 5 minutes you can join the world's biggest networked computer and get
us closer sooner. Watch the video.
http://folding.stanford.edu/
http://Van.Tuyl.eu/
http://members.chello.nl/hjgtuyl/tourdemonad.html
Haskell programming
--
More information about the Haskell-Cafe
mailing list