Index Int wrote
This is getting ridiculous. The main problem with the `Foldable` instance for tuples seems to be that it's asymmetric (takes only the second element into account). Yet tuples are already asymmetric given their `Functor` instance! No one seems to complain about that although for a beginner it's a total WAT (judging from my own experience and people that I explained Haskell to). Why does `succ <$> (1, 2)` evaluate to `(1, 3)` and not `(2, 3)`? Current definitions are entirely consistent, and consistency is the most valuable property.
The difference is that Functor over tuples has some debatable, although arguably misleading uses, but Foldable has no sensible uses whatsoever. Index Int wrote
And given that `Traversable` gives a rise to a `Foldable` similarly to how a `Monad` gives a rise to an `Applicative`, it is the same stupid mistake not to reflect this relation in the type system.
The Monad definition actually uses the Applicative instance. Traversable makes no use of Foldable. -- View this message in context: http://haskell.1045720.n5.nabble.com/Proposal-Add-conspicuously-missing-Func... Sent from the Haskell - Libraries mailing list archive at Nabble.com.