Proposals and owners

[Ross Paterson]

On Thu, Aug 20, 2009 at 01:45:08PM +0100, Simon Marlow wrote:
> On 08/08/2009 10:24, Ross Paterson wrote:
> >On Sat, Aug 08, 2009 at 10:09:38AM +0100, Iavor Diatchki wrote:
> >>I thought that the intended semantics was supposed to be that the only
> >>element is bottom (hence the proposal to add a related empty case
> >>construct)?
> >
> >If that were the case, a compiler could legitimately discard any value
> >of such a type, because it could be easily reconstructed.  I don't
> >think that is what is intended.
> 
> Just in case this question is still open: an empty data declaration
> declares a type that has exactly zero constructors, not an abstract
> type.  What would it mean to define an abstract types?  Haskell only
> allows one definition of any given type.

Yes, I take it back.  Such types are typically used as phantom type
arguments, e.g. the argument of Ptr, so the question I raised doesn't
arise.