PROPOSAL(S): threadWaitError and threadWaitErrorSTM

Merijn Verstraaten merijn at
Sun Mar 16 17:16:08 UTC 2014

I just went with the common documentation name, I know this includes out-of-band data, etc. If it makes you happier, feel free to consider this proposal with s/Error/Exceptional, regardless of how it's called, it'd be nice if we could use this from within Haskell.


On Mar 16, 2014, at 16:09 , Brandon Allbery wrote:

> On Sun, Mar 16, 2014 at 10:25 AM, Merijn Verstraaten <merijn at> wrote:
> threadWaitError :: Fd -> IO ()
> threadWaitErrorSTM :: Fd -> IO (STM (), IO ())
> to allow for blocking on detecting error condition on file descriptors, similar to what C's select() allows.
> If you mean the third bitmask, it is not for errors (notwithstanding the documentation on some systems); an "exceptional condition" is not an error, it's MSG_OOB data. Errors show as "ready" on the appropriate mask (read or write) since a read (resp. write) will return immediately with the error instead of blocking.
> See and for more information.
> -- 
> brandon s allbery kf8nh                               sine nomine associates
> allbery.b at                                  ballbery at
> unix, openafs, kerberos, infrastructure, xmonad

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