Christopher Allen
I don't think it's a good idea to create a dumbed down Prelude and existing resources not covering what programmers need to know in order to actually use Haskell as everyone else uses it is much of the reason I had to write a book to begin with. This type isn't just noise for beginners, it's noise for practitioners too. Consider what I said earlier about a 15 year user of Haskell finding the type confusing and irrelevant.
I agree that until we have shown that these polymorphic uses offer real value in common use-cases we shouldn't allow them to add noise to our common combinator types.
There are a couple good proposals for addressing levity polymorphism leaking into the type. I think the one Ben Gamari had in mind that I thought would be fine is waiting for a patch.
I believe this is on Richard's todo list. Cheers, - Ben