> "Jerzy" == Jerzy Karczmarczuk <[EMAIL PROTECTED]> writes:
> The idea of double lists was to permit a fast two-directional
> navigation,
> and the ease of insertion/deletion.
> But in Haskell, where the beasts are not mutable:
> ... Actually, has anybody really used the
Jerzy Karczmarczuk ([EMAIL PROTECTED]) wrote:
: But in Haskell, where the beasts are not mutable:
:
: ... Actually, has anybody really used them for practical purposes?
I have used doubly linked lists in Haskell about four
years ago to implement a queue from which objects could
be added at fron
Chris Angus:
>
> Would it not be better to tag a start point then we can manipulate this
> easier
> and move it back to a singly linked list etc.
>
> data Db a = Dd (Db a) a (Db a)
> | DStart (Db a) a (Db a)
>
> ...
Well, I am sufficiently old to confess that one of my favourite OO
l
a
right (DStart _ _ a) = a
val (Dd _ x _) = x
val (DStart _ x _) = x
rewind (Dd a _ _) = rewind a
rewind a = a
ffwd (Dd _ _ a) = ffwd a
ffwd a = a
> -Original Message-
> From: Jerzy Karczmarczuk [mailto:[EMAIL PROTECTED]]
> Sent: 28 April 2000 11:12
> Cc: [EMAIL PROTECTED]
> Subje
> -Original Message-
> From: Peter Hancock [mailto:[EMAIL PROTECTED]]
> Sent: 28 April 2000 10:23
> To: [EMAIL PROTECTED]
> Cc: [EMAIL PROTECTED]
> Subject: Re: doubly linked list
>
>
> >>>>> "Jan" == Jan Kort <[EMAIL PROTECTED]
> "Jan" == Jan Kort <[EMAIL PROTECTED]> writes:
> Anyway, a doubly linked list could be defined like this:
That was very interesting. It seems to generalise to put
back-pointers and other context info in a variety of data
structures. This seems a pretty performance-enhancing thing to do
> Jan Brosius wrote:
> I wonder if it is possible to simulate a doubly linked list in
> Haskell.
... and the number of answers was impressive...
Want some more?
This is a short for *making* true double
lists, and as an extra bonus it is circular. Slightly longer than
the solution of Jan Kort, n
- Original Message -
From: Chris Okasaki <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Thursday, April 27, 2000 4:13 PM
Subject: Re: doubly linked list
> > I wonder if it is possible to simulate a doubly linked list in
> > Haskell.
>
> Depends on w
Herewith the comp.lang.functional version of my article. I may have
tidied it up a little for the Wiki; if so, those changes are lost. Let
it hereby enter the Haskell List archive!
The following message is a courtesy copy of an article
that has been posted as well.
Matti Nykanen <[EMAIL P
Keith Wansbrough wrote:
>
>
> Good point! I have no idea... it looks like the Wiki has gone AWOL. If someone
>would tell me where my article has gone, I'd be very grateful!
>
If you find it, maybe you could put it in the "Haskell bookshelf" ?
I found very useful and Wiki has been "AWOL" for
Jan Brosius wrote:
> > > I wonder if it is possible to simulate a doubly linked list
> > in Haskell.
I wrote:
> > No need to simulate it... it's perfectly possible. See my
> > Wiki article.
Chris Angus wrote:
> Where is this article.
> I looked on Haskell.org to no avail
Good point! I ha
> I wonder if it is possible to simulate a doubly linked list in
> Haskell.
Depends on what you mean.
- Using mutable state in a monad you can implement a doubly
linked list directly.
- If you store all the nodes of the doubly linked list in
an array and simulate the pointers with
> I wonder if it is possible to simulate a doubly linked list in Haskell.
No need to simulate it... it's perfectly possible. See my Wiki article.
--KW 8-)
--
: Keith Wansbrough, MSc, BSc(Hons) (Auckland) ---:
: PhD Student, Computer Laboratory, University of Cambridge, UK. :
:
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