[Haskell-cafe] createProcess interferes with sockets?

Donn Cave donn at avvanta.com
Tue Apr 23 08:28:20 CEST 2013

quoth Evan Laforge <qdunkan at gmail.com>,
> and it still waits for the subprocess to complete.  Actually, it looks
> like it's the client's hGetContents, since hGetChar comes back
> immediately.  I guess that's understandable, but even hGetLine blocks.

In the version I was looking at, if I change the server's output
{-- IO.hPutStr hdl "response" --} to "response\n", it works.  Otherwise
hGetLine will still be polling for the newline that will never come.

> System.IO doesn't seem to have a hRead :: Int -> IO String, I guess
> you have to go down to the POSIX fd level, or read char-by-char.

In the present case I believe we'd be talking about
Network.Socket.ByteString.recv.  With a POSIX device like a pipe,
then System.Posix.IO.fdRead.


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