Haskell Foldable Wast

Jeremy voldermort at hotmail.com
Sun Feb 21 12:57:57 UTC 2016

Marcin Mrotek wrote
> I think that, as far as Foldable is concerned, a tuple is equivalent to
> Identity, so this instance is indeed useless. However, Foldable is a
> superclass of Traversable (and it wouldn't make much sense to make these
> classes unrelated, as one can always define folds with `traverse`), so
> I've
> always found it a necessary evil.

Perhaps the case of tuple is evidence that Foldable should *not* be a
superclass of Traversable?

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