[containers] Proposal: Change to the Data.Map Monoid

Edward Kmett ekmett at gmail.com
Tue May 20 21:47:36 UTC 2014

-1 from me as well, though it is a much softer -1 than on the just breaking everyone silently by changing it.

_Lots_ of users initialize empty maps with mempty

Sent from my iPhone

On May 20, 2014, at 4:16 PM, Milan Straka <fox at ucw.cz> wrote:

>>> -----Original message-----
>>> From: Andreas Abel <abela at chalmers.se>
>>> Sent: 20 May 2014, 20:49
>>> I think the Monoid instance for Data.Map should be *removed*.
>> -----Original message-----
>> From: Johan Tibell <johan.tibell at gmail.com>
>> Sent: 20 May 2014, 21:56
>> -1 to removing the instance. It breaks existing code for negligible
>> benefit: you still have to add newtypes to pick the instance you want.
> -1 from me as well.
> Although I agree that current instance is suboptimal, I do not believe
> the cost of removing it is justified. After all, the instance is not
> completely wrong, just not the one people usually expect.
> Cheers,
> Milan
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