On Mon, 27 Sep 1999, Alex Ferguson wrote:
>
<* edited*>
> > > > 2) Support for TRUE OO style programming.
>
> > No. I mean being able to do things such as.
> >
> > Have a collection of object of a common base class AND be able to up
> > cast them when necessary.
>
> If I understand you correctly, then the best way of doing this would be
> with existentially (boundedly) quantified data types, currently a
> non-standard extention present in hbc (and I think, ghc, these days, not
> sure if it's with the same generality.)
Can some one please fill me in on why existential types are not
part of Haskell 98? Probably this is answered in some paper/statement
that I can read some where? I sort of understand them (* I am still
learning haskell. WOrking through S.T's book right now *) but
not enough perhaps to know why they are not used.
I do prefer that the language not get to much semantics from
its type system, perhaps that the answer is related?
Cheers
