One-shot semantics in GHC event manager

Ben Gamari bgamari.foss at
Fri Oct 17 19:41:50 UTC 2014

Austin Seipp <austin at> writes:

> The catch with such a change is that there is no macro to determine
> whether we're using 7.8.3 or 7.8.4, so it's harder for users to figure
> things out (they have to use `MIN_VERSION_base` from Cabal). But maybe
> that doesn'tm atter too much. So, yes, I think it's doable, but that's
> a sticky bit.
Also, I should mention that as written the patch changes no exported
interfaces. Instead of changing `registerFd` it adds an additional
variant `registerFd'` which allows the user to specify a lifetime.

That being said, I'm personally not terribly fond of adding these sorts
of backwards compatibility variants unless really necessary. Given that
this is such a low-visibility interface we may want to consider just
modifying `registerFd` and avoid further polluting the namespace (this
would be the third exported variant of `registerFd`).


 - Ben
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