question about kinds

Ashley Yakeley
Fri, 18 Jan 2002 16:21:26 -0800

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