[racket] doubly linked list lib

Thank you very much, that looks good.

Laurent

On Tue, Aug 30, 2011 at 17:08, Sam Tobin-Hochstadt <samth at ccs.neu.edu>wrote:

> I think there are some purely functional data structures that you can
> use here.  Two examples:
>
>  - Random Access Lists implemented in Hari Prashanth's Typed Purely
> Functional Data Structures [1]
>   Some of the other data structures here, such as VLists, may also be
> helpful.
>
>  - David Van Horn's RAList package [2]
>
> [1]
> http://planet.plt-scheme.org/package-source/krhari/pfds.plt/1/5/planet-docs/functional-data-structures/Random_Access_Lists.html
> [2]
> http://planet.racket-lang.org/display.ss?package=ralist.plt&owner=dvanhorn
>
> On Tue, Aug 30, 2011 at 3:18 AM, Laurent <laurent.orseau at gmail.com> wrote:
> > Thank you very much for this nice intermediate solution, though I need
> > constant-time append, split, insert, remove, + pointers to items, etc.
> > Mutation does seem unavoidable, right.
> > I started my own lib, but if something already exists, I'm still
> interested.
> >
> > The purpose is to make a hash with bounded memory, with replacement of
> > oldest items, or barely used items, or some other replacement criterion.
> >
> > The final purpose is to make a memoization form with bounded memory, or
> > growing memory but with frequent removal of selected items. If I have
> time
> > to get there.
> >
> > I'll keep the zipper in mind for other purposes though!
> >
> > Laurent
> >
> > On Tue, Aug 30, 2011 at 08:35, Danny Yoo <dyoo at cs.wpi.edu> wrote:
> >>
> >> > Nothing obvious, no. But Racket is designed to encourage programming
> >> > without
> >> > mutation, and doubly linked lists require mutation.
> >> >
> >> > It's very likely a zipper will do what you want. A zipper is much
> easier
> >> > to
> >> > implement than a doubly linked list, and has similar performance and
> >> > uses.
> >>
> >>
> >> To supplement, here are very old notes I wrote to myself on the kind
> >> of list zipper that Neil is presenting:
> >>
> >>    https://hkn.eecs.berkeley.edu/~dyoo/plt/zippers.txt
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>
>
>
> --
> sam th
> samth at ccs.neu.edu
>
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