Re: [Haskell-beginners] merge two handles

It probably has to do more with parenthesis than anything: forever $ atomically $ readTchan chan >>= print forever $ (atomically $ readTchan chan) >>= print That might work. Once you get the types to line up, that should work. On Tue, Jun 14, 2011 at 11:26 AM, Manfred Lotz wrote:

On Mon, 13 Jun 2011 15:14:26 -0500 Antoine Latter wrote:

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On Mon, Jun 13, 2011 at 1:14 PM, Manfred Lotz wrote:

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On Mon, 13 Jun 2011 12:51:02 -0500 Antoine Latter wrote:

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On Mon, Jun 13, 2011 at 12:35 PM, Manfred Lotz wrote:

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Hi all, I have two handles where I get stdout resp. stderr from a command output.

Is it possible to merge those two handles so that I get a new input handle in a way that data can be read from the new handle whenever it is available from either of the two original handles?

Does what you're doing strictly need to be a handle?

One thing you could try is is using an IO Channel: http://hackage.haskell.org/packages/archive/base/latest/doc/html/Control-Con...

Hmm, not quite sure. I was asking about handles because I use:

(_ ,Just hout ,Just herr ,p) <- createProcess (proc cmd parms) {    std_out = CreatePipe,    std_err = CreatePipe  }

which gives me handles to deal with.

You could create the pipe yourself, and then call 'createProcess' with 'UseHandle' instead, passing the same handle to both std_out and std_error.

On a unix-y system you can do this with the functions in System.Posix.IO.

I'm not sure what you would do on windows. This might be a good

I'm on a Linux system. Don't use Windows.

Thanks for pointing to this. In the meantime I found something similar in the online book "Real World Haskell". So I have something to try out.

-- Manfred

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