I wrote:
> I have never seen anyone use the technique in any distributed Haskell
code.
> Gerard Huet wrote the article that appeared in JFP, and I believe he
> remarked that they had used the technique to represent ASTs in a
structural
> editor (perhaps in the Coq distribution?).
Sorry, let me improve this:
Huet said they had used the technique to represent _positions_ in ASTs in a
structural editor, and to efficiently implement _editing without imperative
constructs_. This is possible because the navigation functions on a
Zipper-style first-order language are (with some exceptions) mostly constant
order, and so are the modification functions. You don't have to copy the
whole tree to modify it, since you can explicitly manipulate the context of
just the expression which is going to be modified.
Also, I didn't mention that Coq is (now) written in Ocaml.
--FAC