On Mon, 27 Sep 2004 14:11:30 +0100, Jon Harrop <jon@jdh30.plus.com> wrote:
> > For the writter of the function there is a big difference, especially
> > if it has to write the specialized versions.
> 
> The equivalent to the writer of fold is the writer of an iterator. You have to
> write specialized versions for each type of iterator just as you would have
> to write your own fold.

That's why I said iterators are another level of abstraction. The
difference is that after you write the iterators code for a new
sequence-like data structure all the "generic" functions, not only
fold but also map and others, will automagically work on them. The
simplest form of an "iterator" is implementing  a "next" function for
all sequences (although in this situation it is more of an
"enumeration").

You should really check out the article cited by Vasili. It seems that
we understend different things by "functional equivalent of an
iterator", since you talk about the advantage of being able of going
backwards a.s.o. which really is an irrelevant advantage.

regards,
 radu

-------------------
To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr
Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/
Beginner's list: http://groups.yahoo.com/group/ocaml_beginners