"One goal here is that people should be able to use methods from these modules without the need of a qualified import -- i.e. to prevent clash in the namespace, by resolving such in favor of the more generalized versions. Additionally, there are some new methods added to the Foldable class because it seems to be the "right" thing."

Before FTP, I would have to write this to use Foldable/Traversable:

    import qualified Data.Foldable as F

The import is qualified as to not collide with the Prelude.

If I have code that needs to be compatible with more than one GHC release (I typically need compatibility with the last 3 major releases), what do I have to write post-FTP? Since I cannot rely on the Prelude being generalized (because I might be compiling with a pre-FTP compiler) I need to either write:

    #if MIN_VERSION_base(x,y,z)

    -- Get Foldable etc from Prelude

    #else

    import Data.Foldable (...)

    import Prelude hiding (...)  -- the same

    #endif

Which is terrible. Alternatively I can write

    import qualified Data.Foldable as F

but now nothing is gained over the pre-FTP state. Only after 3+ years (at the current GHC release phase) I can drop that one extra import. One out of perhaps 20. That seems quite a small gain given that we will then have made Data.List a very confusing module (it's essentially Data.Foldable under a different name), broken some code due to added type ambiguity, and also removed one of the simpler ways to remove that ambiguity, which would have been to import one of the monomorphic list functions that no longer exist.