Re: [Haskell-beginners] Named Pipes Et Cetera

Here's the uname -a output: $ uname -a Linux pc207 2.6.30.10-105.2.23.fc11.x86_64 #1 SMP Thu Feb 11 07:06:34 UTC 2010 x86_64 x86_64 x86_64 GNU/Linux Patrick On Tue, Nov 23, 2010 at 10:36 AM, Patrick LeBoutillier wrote:

On Tue, Nov 23, 2010 at 9:13 AM, matthew coolbeth wrote:

...

That's interesting.  This was using my source code?

Yes, as is. I compiled it with "ghc --make pipe.hs".

I'm running Fedora 10 x64 with: $ ghc --version The Glorious Glasgow Haskell Compilation System, version 6.10.1

Patrick

...

On mine (also a Linux box), it exited immediately, giving me no opportunity to write to the pipe.

On 2010-11-23, Patrick LeBoutillier wrote:

...

Matthew,

Does it return immediately when you start it or only when you try to write to the pipe with some client?

Here's what I get on my Linux box:

$ rm /tmp/dld.fifo && ./pipe & [1] 8603 $ echo -e "1\n2\n3" > /tmp/dld.fifo 1 2 3 pipe: /tmp/dld.fifo: hGetLine: end of file

Patrick

On Tue, Nov 23, 2010 at 7:55 AM, matthew coolbeth wrote:

...

Hello, all.

Three questions:

1> What, if anything, can I do in a Haskell program to do blocking reads from a Linux FIFO?  For the curious, there is a small program below that doesn't block, but immediately terminates because of an EOF

2> How could I have found the answer to this question on my own? (The documentation that Google found for me was not completely adequate)

3> Is this sort of question generally regarded as too unixy or not haskelly enough to be appropriate for this mailing list?

Thanks.

--BEGIN PROGRAM-- module Main () where

import Control.Monad import System.IO import System.Posix.Files

pipeString = "/tmp/dld.fifo"

main :: IO () main = do        createNamedPipe pipeString $ unionFileModes ownerReadMode ownerWriteMode        pipe <- openFile pipeString ReadMode        forever (hGetLine pipe >>= putStrLn)

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-- ===================== Patrick LeBoutillier Rosemère, Québec, Canada

-- mac

-- ===================== Patrick LeBoutillier Rosemère, Québec, Canada

-- ===================== Patrick LeBoutillier Rosemère, Québec, Canada