At 2002-01-18 13:10, Hal Daume III wrote:

Now, I want to say that if some data type 'd' is Traversable and another data type 'e' is Traversable, then the "combined data type" is Traversable. That is, for example, I want to say that a Tree of Lists is traversable, or that a List of Trees, or a List of Lists is traversable.

If the Tree type constructor is Traversable, then it's Traversable no matter what it's applied to. You've provided a instance for traversing "Trees of anything", it's going to overlap with any instance for "Trees of Lists". -- Ashley Yakeley, Seattle WA