Re: [Ocaml-lib-devel] Proposal : BinTree

[Nicolas C. <war...@fr...>]

>     is there any advantage of
>
> > type ('a,'b) t = {
> > cmp : ('a -> 'a -> int);
> > t : ('a ,'b) tree ref;
> > }
>
> over:
>
> type ('a,'b) t = {
>     cmp : ('a -> 'a -> int);
>     mutable t : ('a, 'b) tree;
> }
>
> Doesn't the first version require a little bit more memory?
> I don't think it's a big deal, but...

It's for recursion, since are left and right trees are both ('a , 'b ) tree
ref. The problem is that you cannot pass a mutable field to a function
like a ref.

> Also, what are the relative advantages of having this vs.
> putting a mutable wrapper around Map?  Map, if I'm not mistaken,
> makes some guarantees of the trees being balanced (both add
> and remove in Map call the balancing function).

Map does not allow to have several items with the same key in it.
Calling add is replacing the current binded item if any.
I think it's more convenient to have a structure that can "shadow" items
just like Hashtbl do.

Nicolas Cannasse