<div dir="ltr">That leads to a ton of ever MORE nonsensical consequences like not being to weaken calls to mapM (which uses Traversable) to mapM_(which needs only Foldable) or doubling the number of combinators we have all over again for random prescriptive reasons, right after we just starting finally healing the last source of needless duplication (Applicative not being a superclass of Monad).<div><br></div><div>-Edward</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Sun, Feb 21, 2016 at 7:57 AM, Jeremy <span dir="ltr"><<a href="mailto:voldermort@hotmail.com" target="_blank">voldermort@hotmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Marcin Mrotek wrote<br>
<span class="">> I think that, as far as Foldable is concerned, a tuple is equivalent to<br>
> Identity, so this instance is indeed useless. However, Foldable is a<br>
> superclass of Traversable (and it wouldn't make much sense to make these<br>
> classes unrelated, as one can always define folds with `traverse`), so<br>
> I've<br>
> always found it a necessary evil.<br>
<br>
</span>Perhaps the case of tuple is evidence that Foldable should *not* be a<br>
superclass of Traversable?<br>
<br>
<br>
<br>
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