GHC 7.8.3 thread hang

Gregory Collins greg at
Tue Nov 11 16:45:04 UTC 2014

On Mon, Nov 10, 2014 at 11:11 PM, Michael Jones <mike at> wrote:

>        ec <- return $ encode command
>        traceEventIO $ "sendCommand: encoded"
>        l <- ec `seq` return $ BSL.length ec

Your encode function probably loops on some inputs. When you call "return $
foo", foo is not forced; that doesn't happen in your example until
BSL.length forces its input. If I'm right, changing the first line to
"return $! encode command" will move the hang to before the call to

Gregory Collins <greg at>
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