Re: Proposal: Show and Read for Data.Ord.Down

I agree. I really do wish that derived Read/Show for single-parameter constructors didn't try to show the record syntax. There is another approach: I often just wind up writing the 4 lines of Read/Show for simple data types / newtypes. This avoids cluttering my debugging output, while keeping it as a field accessor so end users can still just import Foo (Down(..)) and be sure getDown comes along for the ride. -Edward On Fri, Sep 27, 2013 at 5:06 AM, Ross Paterson wrote:

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

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On 26 September 2013 18:03, David Luposchainsky wrote:

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On 2013-09-26 06:50, Edward A Kmett wrote:

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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. _______________________________________________ Libraries mailing list Libraries@haskell.org http://www.haskell.org/mailman/listinfo/libraries