[Ocaml-lib-devel] Re: Re: Dllist ? IndexTree ?

[Jesse G. <je...@wi...>]

Brian Hurt wrote:

> On Fri, 10 Sep 2004, Jesse Guardiani wrote:
> 
>> Actually, I tried this before I submitted the current implementation and
>> I couldn't get it to work. The problem seemed to be that Dllist has no
>> concept of Empty, so the length function becomes really difficult to
>> implement.
> 
> I moved the concept of "empty" one level up in my implementation.  This is
> because I didn't want to deal with options on the next/prev links.
> 
>> 
>> Brian, do you think it's possible to implement enums without the "valid"
>> test? If everyone thinks it's possible then I'll give it another shot. I
>> just didn't have much luck the first time around.
> 
> Actually, changing things so that x.next == x is the sign of the end of
> the list should make enums easier.
> 
> let rec enum_done = { data = Obj.magic (); next = enum_done;
>                       prev = enum_done };;
> 
> let enum dlst =
>     match dlst.head with

The concept of "head" was removed along with the concept of "Empty"
in the last release.


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