Proposal: Show and Read for Data.Ord.Down

[Ross Paterson]

On Thu, Sep 26, 2013 at 06:16:57PM +1000, Ivan Lazar Miljenovic wrote:
> On 26 September 2013 18:03, David Luposchainsky
> <dluposchainsky at googlemail.com> wrote:
> > On 2013-09-26 06:50, Edward A Kmett wrote:
> >> I strongly favor creating instances like this.
> >>
> >> Not having them just makes the world more painful to debug code to
> >> make a normative point and leads to greater code fragmentation when
> >> someone else has another stance.
> >
> > I agree. Being able to look at some value "the dirty way" is an
> > important use case of Show (be it as a return value or via trace), and I
> > see no reason for any datatype to not support Show when it could.
> >
> > On Read I don't have an opinion because I usually try to avoid it :-)
> >
> > +1
> 
> +1 from me as well; furthermore, how about an "unDown :: Down a -> a"
> record function or some such just to avoid the "\(Down x) -> x" usage
> like how Krzysztof described?

Making it a field will complicate the derived Read and Show instances.
That can be avoided by adding it as a separate function.