[Haskell-cafe] Taking over `data-default-*`

[Marco Zocca]

While I very much agree with all of you on the need for solid
typeclass laws, I think Default still has its place in the library
author toolkit .

Think for example of configuration data for very flexible
functionality such as plotting.

On the other hand, if it's such a bad idea, what's a good course of
action in this case ? Take over and deprecate ?





On Tue, May 8, 2018 at 11:21 AM, Chris Wong <lambda.fairy at gmail.com> wrote:
> On Tue, May 8, 2018 at 9:10 PM, Marco Zocca <zocca.marco at gmail.com> wrote:
>>
>> data-default alone is depended on by > 500 packages :
>> http://packdeps.haskellers.com/reverse/data-default
>>
>> Could you motivate why it's not a good idea ?
>>
>
> I can think of two reasons:
>
> - It has no laws, so there's formal specification that tells us whether an
> instance is "correct" or not.
>
> - Type classes are useful when there is a large family of generic operations
> that can work with them. For example, the utility functions in Control.Monad
> [1] are used in all kinds of Haskell programs. But there are no such generic
> operations that apply to all Default instances.
>
> That said -- as you note, it's has quite a few dependents so it's great that
> someone is stepping up to maintain it regardless.
>
> Chris
>
> [1]
> https://hackage.haskell.org/package/base-4.11.1.0/docs/Control-Monad.html#g:4
>
>>
>>
>> On Tue, May 8, 2018 at 11:02 AM, Christopher Allen <cma at bitemyapp.com>
>> wrote:
>> > Is this something folks still think is a good idea? I purge
>> > Data.Default from projects I work on.
>> >
>> > On Tue, May 8, 2018 at 3:58 AM, Marco Zocca <zocca.marco at gmail.com>
>> > wrote:
>> >> Dear all,
>> >>
>> >>   I've been increasingly relying on data-default-class, but sadly it
>> >> doesn't look like it's currently maintained; there are some tickets on
>> >> the github issue tracker that would need some attention.
>> >>
>> >> I have tried contacting the authro/current maintainer Lukas Mai (CC'd)
>> >> by email but have not received an answer so far (I hope he's doing
>> >> well, btw).
>> >>
>> >> This is my first public request for taking over the `data-default`
>> >> family of packages:
>> >>
>> >> data-default-class
>> >> data-default-instances-base
>> >> data-default-instances-containers
>> >> data-default-instances-dlist
>> >> data-default-instances-old-locale
>> >> data-default
>> >>
>> >> Kind regards,
>> >> Marco Zocca
>> >> (http://hackage.haskell.org/user/ocramz)
>> >> _______________________________________________
>> >> Libraries mailing list
>> >> Libraries at haskell.org
>> >> http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries
>> >
>> >
>> >
>> > --
>> > Chris Allen
>> > Currently working on http://haskellbook.com
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>
>
>
>
> --
> Chris Wong (https://lambda.xyz)
>
> "I had not the vaguest idea what this meant and when I could not remember
> the words, my tutor threw the book at my head, which did not stimulate my
> intellect in any way." -- Bertrand Russell