[Haskell-cafe] Re: standard poll/select interface

John Meacham john at repetae.net
Tue Feb 21 19:32:34 EST 2006

On Tue, Feb 21, 2006 at 01:15:48PM +0000, Simon Marlow wrote:
> I agree that a generic select/poll interface would be nice.  If it was 
> in terms of Handles though, that's not useful for implementing the I/O 
> library.  If it was in terms of FDs, that's not portable - we'd need a 
> separate one for Windows.  How would you design it?

Yeah, this is why I have held off on a specific design until we get a
better idea of what the new IO library will look like. I am thinking it
will have to involve some abstract event source type with primitive
routines for creating this type from things like handles,fds, or
anything else we might want to wait on. so it is system-extendable in
that sense in that implementations can just provide new event source
creation primitives. 

The other advantage of this sort of thing is that you would want things
like the X11 library to be able to provide an event source for when an
X11 event is ready to be read so you can seamlessly integrate your X11
loop into your main one.

The X11 library would create such an event source from the underlying
socket but just return the abstract event source so the implementation
can change (perhaps when using a shared memory based system like D11 for
instance) without affecting how the user uses the library in a portable

I will try to come up with something concrete for us to look at that we
can modify as the rest of the IO library congeals.


John Meacham - ⑆repetae.net⑆john⑈

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