Re: [Ocaml-lib-devel] Re: [PATCH] updated enum: now concat uses t.fast

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

> > I'll try to review theses patch when I have some time.
> > I think it's good idea to remove the try..catch blocks when we have a
"fast"
> > count in concat and append, because they occur in each call to next .
But
> > for fold / iter , I'm not sure, mainly because a fast count can still be
> > O(N) and cost more than having one try...catch block setuped. Could you
do
> > some benchs using ExtList.enum instead of Enum.init ? The "fast" count
is
> > O(N) here in this case ( but is computed only once ). With big lists (
"when
> > we need speed" ) I'm pretty sure it will be better not to call count.
>
> I was operating under the assumption that "fast" would be set only for
> data structures that had their count readily available -- for
> instance, dynarray and init.

To get this behavior, it would mean that the user have to specify if it's
count() function is "fast" or not when constructing an Enum . Then it's
getting quite difficult for an new user to understand how to create Enums
and we're loosing the simplicity of them . "fast" should remain an internal
optimisation to distinguish the cases when we are calling "force" or not
when counting elements ( the minor speed improvement does not worth having a
more complex interface ).

Nicolas Cannasse