> Jerzy Karczmarczuk wrote:
>
> Yes, Simula-67.
>
> Actually *they did* that. A "node" had two sub-classes, the link and the
> head, and the link chain was doubly attached to the head. This structure
> has been havily used for the maintenance of the co-routine bedlam
> exploited in simulation programs.
>
> 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 them for practical purposes?
>
> Jerzy Karczmarczuk
> Caen, France
>
>
Well I want to see the simulation of a mutable doubly linked list too.
The author of Lout writes in his documentation that after much searching
he
was compelled
to use doubly linked C lists.
In Ocaml there was recently an online English version about using pointers
in Ocaml
(if people would like to do this) . I have got yesterday the solution of
implementing
doubly linked lists, it was rather short.
I also wonder how one could simulate objects with mutable state in Haskell.
Another question : is there any way to interrogate the typechecker from
within a Haskell program?
Could this be put on the wishlist?
Friendly
Jan Brosius
