[Proposal] Add instance Monoid a => Monoid (Const a b)

Edward A Kmett ekmett at gmail.com
Sat Oct 12 22:16:09 UTC 2013

> On Oct 12, 2013, at 3:15 PM, Ross Paterson <R.Paterson at city.ac.uk> wrote:
>> On Sat, Oct 12, 2013 at 01:32:33PM -0400, Edward Kmett wrote:
>> I am strongly in favor of removing Constant from transformers.
> No objection to that: we obviously don't need both.
>> It isn't used by the vast majority of the ecosystem, but Const is in very
>> active use.
>> The only major consumer of Constant at this time I think is Rusell O'Connor's
>> multiplate library.
> And presumably you want to keep the shorter name for backward compatibility.

>> On a related note Simon recently asked the core libraries committee if we
>> should move Data.Functor.Identity into base.
>> I'm very strongly inclined to say yes, as was the rest of the committee.
>> Do you have any objection there?
> I don't object to moving Data.Functor.Identity, but I wish that
> discussion had happened in a place where the rest of us could see it.
> On this tangent, I note on
> http://www.haskell.org/haskellwiki/Core_Libraries_Committee
> that the process is described as:
>    It is expected the committee will discuss any matters brought
>    to it amongst themselves, and if they think appropriate, with
>    the wider community, to try to reach consensus.  Ultimately,
>    the committee will make decisions by more than half of the
>    membership voting for a particular outcome.  These rules of
>    operation may also be changed in the same way.
> That's a more closed model than I thought was envisaged when the
> committee was set up, and I think it's problematic.  I'd suggest that
> open discussion with the committee making the final decision is likely
> to produce better results.

We're trying to carry out most conversations here on libraries@

This was literally just a question posed directly to that mailing list by Simon the other day seeking feedback in advance of his talk and a couple of short replies from folks thinking it'd be a good idea. Not a formal proposal.

I agree it really probably belongs out here, it was just something I felt I should mention while we were on a related topic. I'm happy to turn it into a more formal proposal with a capital P.

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