[m-dev.] discussion about the implementation of compact type representations

[Zoltan Somogyi]

On Tue, 31 Oct 2017 03:24:48 +1100, Mark Brown <mark at mercurylang.org> wrote:

> >> - If the argument of the function symbol has an existential type,
> >>   that should not be an error, but should make the type NOT a notag type.
> 
> How about if it's an existentially typed dummy type, such as
> 
>   :- type foo ---> some [T] foo(unit(T)).
> 
> If there's just a type_info in there, that could also be considered
> notag. Is it worth including this case?

Have you ever seen such a type in real life? I haven't, and I would be
surprised if you have. I think that makes it pretty clear that optimizing
the representation of such types is not a priority.

Zoltan.