Using existential types

[Tomasz Zielonka]

On Wed, Oct 08, 2003 at 09:40:35AM -0700, Mike Gunter wrote:
> 
> Jan-Willem Maessen <jmaessen at MIT.EDU> writes:
> 
> > Tomasz Zielonka <t.zielonka at zodiac.mimuw.edu.pl> wrote:
> > [...]
> > > data Stat i o = -- aggregate function taking i's on input and producing o
> > >     forall s. Stat
> > > 	s		-- init
> > > 	(s -> i -> s)	-- update
> > > 	(s -> o)	-- result
> > [...]
> > * But it bugs me that an awful lot of examples of existential typing
> >   could be obtained simply by currying / lazy evaluation.  In this
> >   case, however, the "update" function lets us absorb additional input
> >   as in the subsequent message (which I've now accidentally deleted):
> 
> I'm not convinced that existentials are needed here.
> 
> 	mike

You are right. When I came up with updateStat, I could go futher and
remove existential type.

Best regards,
Tom

-- 
.signature: Too many levels of symbolic links