darcs patch: Make toList a member of Foldable

[Eelis van der Weegen]

On 2010-04-28 00:37, Ross Paterson wrote:
> The instance for NonEmpty should be
> 
>   instance Foldable NonEmpty where
>     foldr f x (NonEmpty h t) = f h (foldr f x t)
> 
> which would then rely on the optimization of the [] instance.

Even with such an optimal foldr, the generic toList would still
reconstruct the whole list, which would still be O(n) instead of O(1), no?