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. -Edward

On Sep 25, 2013, at 4:36 PM, Joachim Breitner wrote:

Hi,

Am Mittwoch, den 25.09.2013, 15:17 +0200 schrieb Krzysztof Gogolewski:

...

I propose to add derived Show and Read instances to Data.Ord.Down. This should be uncontroversial. Any thoughts?

I could imagine that such instances were intentionally not put there because the author of Down has intended it to be used only “temporarily”, e.g. map (\(Down x) -> x) . sort . map Down so the absence of the instances encourage that usage pattern.

Not sure though if base should be encouraging certain usage patterns. Also, Show is useful for debugging.

A mildly positive *shrug* from me.

Greetings Joachim

-- Joachim “nomeata” Breitner mail@joachim-breitner.de • http://www.joachim-breitner.de/ Jabber: nomeata@joachim-breitner.de • GPG-Key: 0x4743206C Debian Developer: nomeata@debian.org _______________________________________________ Libraries mailing list Libraries@haskell.org http://www.haskell.org/mailman/listinfo/libraries

On 26 September 2013 18:03, David Luposchainsky 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? -- Ivan Lazar Miljenovic Ivan.Miljenovic@gmail.com http://IvanMiljenovic.wordpress.com

On Fri, Sep 27, 2013 at 1:23 AM, Ben Millwood wrote:

On Thu, Sep 26, 2013 at 06:16:57PM +1000, Ivan Lazar Miljenovic wrote:

...

+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?

I vote for `getDown` as it's just not often enough I feel like my Haskell code is instructing me to party.

Calling it 'getDown' would also be consistent with the newtypes in Data.Monoid. Erik

On 2013-09-27 15:40, Edward Kmett wrote:

+1 for getDown

This kind of makes me wish there was an Up newtype. Regards,

On 2013-09-27 23:55, David Luposchainsky wrote:

On 2013-09-27 23:41, Bardur Arantsson wrote:

...

This kind of makes me wish there was an Up newtype.

Before somebody suggests renaming Identity, let's stop the bikeshedding and push this trivial change?

I don't really think humour (or attempts at such) count as bikeshedding, but whatevs... :) +1 to the OP.

On Thu, Sep 26, 2013 at 06:16:57PM +1000, Ivan Lazar Miljenovic wrote:

On 26 September 2013 18:03, David Luposchainsky 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.

That's exactly the derived instance that would be generated: instance Show a => Show (Down a) where ... Erik On Thu, Sep 26, 2013 at 12:59 PM, Herbert Valerio Riedel wrote:

On 2013-09-25 at 15:17:30 +0200, Krzysztof Gogolewski wrote:

...

Hello,

I propose to add derived Show and Read instances to Data.Ord.Down. This should be uncontroversial. Any thoughts?

...wouldn't that require the wrapped type to provide 'Show' as well? _______________________________________________ Libraries mailing list Libraries@haskell.org http://www.haskell.org/mailman/listinfo/libraries

On 26 September 2013 22:12, Herbert Valerio Riedel wrote:

On 2013-09-26 at 13:15:00 +0200, Erik Hesselink wrote:

...

That's exactly the derived instance that would be generated:

instance Show a => Show (Down a) where ...

...in that case, +1 from me :-)

(I assumed wrongly this was about adding "derived (Show,Read)" to 'Down')

It is.... that's just what the derived instance would be. -- Ivan Lazar Miljenovic Ivan.Miljenovic@gmail.com http://IvanMiljenovic.wordpress.com