Strange error in show for datatype
Thu, 4 Oct 2001 14:29:43 +0100
On Thu, Oct 04, 2001 at 09:23:10AM +0000, Marcin 'Qrczak' Kowalczyk wrote:
> Thu, 4 Oct 2001 00:36:55 -0700, Simon Peyton-Jones <firstname.lastname@example.org> pisze:
> > Void was a type with one element. What we really want here is
> > a type with no elements. It's also useful to be able to introduce
> > such empty types for phantom-type purposes, so GHC now lets you say
> > data T
> > and get a type T with no values.
> I think both Void and T have bottom, and both have no other values.
So this extension adds something we already have in Haskell 98, with either
newtype Void = Void Void
or data Void = Void !Void
(as I think Patrik Jansson pointed out)