[Haskell-cafe] Textbook example of instance Foldable ((,) a)

[David Feuer]

The expectation that length = getSum . foldMap (Sum . const 1)

On Mon, Nov 23, 2020, 10:21 AM Manuel Schneckenreither <
manuel.schnecki at gmail.com> wrote:

>     >>>>> "HT" == Henning Thielemann <lemming at henning-thielemann.de>
> writes:
>
>     HT> "length (a,b) == 1" is only a consequence of defining instance
>     HT> Foldable for pairs. It was not the argument to implement that
>     HT> instance, at all.
>
> What was the argument to use 1, not 2 for instance?
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