Haskell Foldable Wast

amindfv at gmail.com amindfv at gmail.com
Sun Feb 21 17:17:05 UTC 2016

I think the ship has sailed on big breaking changes to Foldable/Traversable -- an argument could be made to remove a wonky instance, but removing Foldable as a superclass seems to me like a much bigger change.


> El 21 feb 2016, a las 07:57, Jeremy <voldermort at hotmail.com> escribió:
> 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?
> --
> View this message in context: http://haskell.1045720.n5.nabble.com/Proposal-Add-conspicuously-missing-Functor-instances-for-tuples-tp5827530p5830710.html
> Sent from the Haskell - Libraries mailing list archive at Nabble.com.
> _______________________________________________
> Libraries mailing list
> Libraries at haskell.org
> http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries

More information about the Libraries mailing list