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From: Goswin von Brederlow <goswin-v-b@web.de>
To: Gabriel Scherer <gabriel.scherer@gmail.com>
Cc: Goswin von Brederlow <goswin-v-b@web.de>,
        Edgar Friendly <thelema314@gmail.com>, caml-list@inria.fr
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Subject: Re: [Caml-list] Can one implement greedy/inline data structures in ocaml?

Gabriel Scherer <gabriel.scherer@gmail.com> writes:

>> So then you need mutable option types or mutables that you initialize
>> with dummy values and then overwrite with the real thing once all
>> members of a cycle are created. Or some other trickery to make it
>> work. Overall cycles are generally not good.
>
> I believe the trick you need (either passing a dummy value of your
> type, or Obj.magic) is less ugly that your Camlp4 solution for inline
> access.
> If I really needed absolute performance, I'd use the inline version
> just like in C, with mutable fields, but without preprocessor sugar.
> Preprocessing could avoid a bit of duplication (corresponding to
> manual inlining) on the structure-definition side, but wouldn't
> simplify the structure-using code much.

How?

type task = {
     mutable all_next : task;
     mutable all_prev : task;
     mutable state_next : task;
     mutable state_prev : tast;
     ...
}

Now how do yout write DList.insert, DList.remove, DList.iter, ...?

I'm looking for some nice tricks using closures, functors, first class
modules or something to make it look pretty and easy to use.

I do have an ugly solution but I'm hoping for some fresh idea not based
on what I already know is ugly. I can't be the only one that found the
need to keep an item in two containers and be able to remove it from
both quickly, right?

MfG
        Goswin