Empty Datatypes in GHC 5?

Alastair David Reid reid@cs.utah.edu
07 Jun 2001 18:55:21 -0600

Ashley Yakeley <ashley@semantic.org> writes:

>  data Zero; data Succ n;

> Unfortunately this is contrary to the Haskell
> Report. Nevertheless, Hugs allows it. But GHC, apparently,
> does not.

Note that Hugs allows it principally so that we can write the following
in the Prelude:

  data Float
  data Double
  data Int
  data Char 

That it's useful for other things is pretty much incidental.

Alastair Reid        reid@cs.utah.edu        http://www.cs.utah.edu/~reid/