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

[David Thomas]

For what it's worth, I'd find Semigroup v => Monoid (Map k v) both
more useful and less surprising than the current unqualified monoid
instance for all maps.  I say +1 if we can find a good way to deal
with the breakage.  -0.1 otherwise - it's a significant concern.

On Wed, May 21, 2014 at 8:52 AM, Edward Kmett <ekmett at gmail.com> wrote:
> There is always the option of folding Default into base, resolving concerns
> about where you get instances for it and the ensuing package explosion once
> and for all.
>
> -Edward
>
>
> On Wed, May 21, 2014 at 11:12 AM, João Cristóvão <jmacristovao at gmail.com>
> wrote:
>>
>> Sorry for continuing the off-topic, and for promoting a package of mine:
>>
>> If you only need the class definition,
>> http://hackage.haskell.org/package/data-default-class is a better choice,
>> with no dependencies.
>>
>> If you prefer a single package with all the dependencies (and with
>> additional generics support), my own fork might be useful:
>> http://hackage.haskell.org/package/data-default-generics
>>
>> Although I mirrored the original package dependencies, many of which might
>> actually be unnecessary... (given the generics implementation).
>>
>> Cheers
>>
>>
>> 2014-05-21 15:59 GMT+01:00 Michael Snoyman <michael at snoyman.com>:
>>
>>> At the risk of veering terribly off-topic... the splitting of
>>> data-default into all of those packages caused me a bunch of dependency
>>> headaches, most of which I still don't fully comprehend. I miss the good ol'
>>> days of a single package.
>>>
>>>
>>> On Wed, May 21, 2014 at 5:53 PM, Edward Kmett <ekmett at gmail.com> wrote:
>>>>
>>>> I find myself rather hesitant to recommend that instantiation of the
>>>> idea ever since it exploded into a half-dozen packages full of orphan
>>>> instances, but yes.
>>>>
>>>> -Edward
>>>>
>>>>
>>>> On Wed, May 21, 2014 at 6:38 AM, Herbert Valerio Riedel <hvr at gnu.org>
>>>> wrote:
>>>>>
>>>>> On 2014-05-21 at 00:23:44 +0200, Andreas Abel wrote:
>>>>> >>> _Lots_ of users initialize empty maps with mempty
>>>>> >
>>>>> > Well, this is another issue, empty should be overloaded via
>>>>> >
>>>>> > class Empty a where
>>>>> >   empty :: a
>>>>>
>>>>> Btw, isn't this what
>>>>>
>>>>>   http://hackage.haskell.org/package/data-default
>>>>>
>>>>> provides?
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>>>>
>>>>
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>>>
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>
>
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