We show how to merge two folds into another fold
`elementwise'. Furthermore, we present a library of (potentially
infinite) ``lists'' represented as folds (aka streams, aka
success-failure-continuation--based generators). Whereas the standard
Prelude functions such as |map| and |take| transform li
Dylan Thurston wrote:
> > The defining equations are: if flst is a value
> > of a type |FR a|, then
> > unFR flst f z = z if flst represents an empty list
> > unFR flst f z = f e (unFR flst' f z)
> > if flst represents the list with the head 'e'
> >
On Tue, Oct 11, 2005 at 05:25:24PM -0700, [EMAIL PROTECTED] wrote:
> First we define the representation of a list as a fold:
>
> > newtype FR a = FR (forall ans. (a -> ans -> ans) -> ans -> ans)
> > unFR (FR x) = x
>
> It has a rank-2 type. The defining equations are: if flst is a value
> of a typ
unctions.html. Also Josef
Svengingsson (ICFP'02). I don't know how these relate to your solution.
Simon
| -Original Message-
| From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
On Behalf Of
| [EMAIL PROTECTED]
| Sent: 12 October 2005 01:25
| To: haskell@haskell.org
| Subject: [Haskel
Hello!
> I'm sure you're aware of the close connection between your FR
> stuff (nice) and the foldr/build list-fusion work?
I am now. Indeed, the 'FR' representation of lists is what one passes
to 'build'. Incidentally, the higher-rank type of FR is a
_requirement_ (otherwise, things won't type
