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 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)