Proposal: split Chan and TChan into read and write ends
lemming at henning-thielemann.de
Sat Oct 27 09:52:13 CEST 2012
On Fri, 26 Oct 2012, Brandon Simmons wrote:
> Hi everybody,
> Just discovered all the great discussion here, and although my
> google-fu turned up no prior discussions on this subject, I apologize
> if it has already been discussed.
> I propose that Chan and TChan should be implemented as a pair of read
> and write ends, initialized as follows:
> newSplitChan :: IO (InChan a, OutChan a)
> I've implemented this already here:
> http://hackage.haskell.org/package/chan-split . You can ignore the
> type classes I've defined; they're there for my own reasons and not
> part of the proposal.
I have implemented something similar in plain Haskell 98:
When using it I found that often there is a clear distinction between
input and output end of a channel but sometimes it is not. E.g. a thread
might send messages to itself. Of course I could pass around both channel
ends in this case.
I don't think it is worth to break the API. I am happy with separate
packages. If the implementors of Control.Concurrent think that the
implementations become cleaner then they might add new modules. This would
allow for a smooth transition.
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