A bug with Sum (as in Monoid)

[Brent Yorgey]

Hint: the problem has nothing to do with zeros.

λ> 0.1 + (0.2 + 0.3) == (0.1 + 0.2) + 0.3
False


On Wed, Nov 6, 2019 at 4:20 PM Dannyu NDos <ndospark320 at gmail.com> wrote:

> Omg, addition is not even associative? The zeros truly ruined everything.
>
> 2019년 11월 7일 (목) 06:58, Brent Yorgey <byorgey at gmail.com>님이 작성:
>
>> How is that worse than the fact that addition is already not associative
>> for floating point types?  At least +0 is really the identity up to (==).
>>
>> On Wed, Nov 6, 2019, 3:49 PM Dannyu NDos <ndospark320 at gmail.com> wrote:
>>
>>> Sum has bug with floating points. Current definition states +0 as the
>>> identity element, while the actual identity is -0 since +0 + -0 = +0.
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>>
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