Why Traversable/Foldable should not be in the Prelude

Summary: For GHC 7.10, Traversable and Foldable are going to be in the Prelude. I missed the original discussion, but I suspect it's a bad idea. Types are how Haskell programmers communicate their intentions to each other. Currently, the Haskell Prelude contains: mapM :: Monad m => (a -> m b) -> [a] -> m [b] As of GHC 7.10, as part of something known as the Burning Bridges Proposal (ticket, discus

[igrep]

“mapM :: (Traversable t, Monad m) => (a -> m b) -> t a -> m (t b)”になっちゃう！？

[ruicc]

GHC7.10のPreludeにTraversable/Foldableが入ろうとしている問題