asum really needs to go into the Foldable class (or something)

[David Feuer]

Well, I guess I can try to answer my own question. The main distinction is
between left-handed and right-handed monoids. So the thing to do is to add
explicitly left-handed and explicitly right-handed versions of these
functions to Data.Foldable.
On Nov 5, 2014 2:03 PM, "David Feuer" <david.feuer at gmail.com> wrote:

> OK, so can you suggest a good implementation of sum or asum or traverse_
> that will work sanely regardless of the monoid? Because I can't think of
> any way to do that. Or can you think of a better way than FoldableMP to
> accomplish that objective?
> On Nov 5, 2014 1:45 PM, "Edward Kmett" <ekmett at gmail.com> wrote:
>
>> Please consider me strongly against such a FoldableMP class.
>>
>> -Edward
>>
>> On Wed, Nov 5, 2014 at 11:42 AM, David Feuer <david.feuer at gmail.com>
>> wrote:
>>
>>> The current definition is "biased", using foldr and <|> instead of
>>> foldMap and the new Alt. This is a bit awkward in the post-BBP world, but
>>> we also don't want to just debias it across the board, because if the
>>> Foldable is holding lists, the debiased version will be very bad.
>>>
>>> More generally, there are a number of Foldable members that are very
>>> awkward, pleading for MPTC, because the sane implementations depend on both
>>> the container type and the element type. I know we're pushing right up
>>> against the deadline for 7.10.1, but the current situation is making me
>>> very nervous.
>>>
>>> David
>>>
>>
>>
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