[Haskell-cafe] Circular pure data structures?

[Antoine Latter]

On Wed, Jul 15, 2009 at 12:13 AM, Eugene Kirpichov<ekirpichov at gmail.com> wrote:
> Zippers come up as the "derivative" of the type; if you haven't yet
> encountered this trick, then first find it :)
>
> Try differentiating your datastructure.
>

Here's a paper with a good introduction to the concept and bibliography:

http://strictlypositive.org/dfordata.pdf

My take on it:

A zipper is the one-hole-context of your data-type plus a focused-on
payload. Data-structure differentiation is the method for deriving the
one-hole-context.

Antoine