Deriving tweaking

[David Feuer]

Excellent!

On Aug 5, 2016 2:32 PM, "Edward Kmett" <ekmett at gmail.com> wrote:

> Done and done! Retroactively. How is that for service? =)
>
> -Edward
>
> On Fri, Aug 5, 2016 at 2:08 PM, David Feuer <david.feuer at gmail.com> wrote:
>
>> I know there's been some discussion about letting users select the
>> deriving mechanism they want, but I'd like to propose a separate tweak to
>> the defaults. Specifically, it's annoying to have to use three pragmas to
>> let me write
>>
>> newtype Foo f a = Foo (f a) deriving (Functor, Foldable, Traversable)
>> data Bar f a = Bar (f a) deriving (Functor, Foldable, Traversable)
>>
>> and more annoying still that I'll end up with Foldable and Functor
>> instances for Foo that may be much worse than GND-derived ones.
>>
>> The tweaks I'm after:
>>
>> 1. Prefer GND to the built-in derivations for Functor and Foldable, and
>> probably also Eq and Ord.
>> 2. Make DeriveTraversable imply DeriveFunctor and DeriveFoldable.
>>
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>>
>
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