[Haskell-cafe] common class for Set (and Map, resp.) implementations with different constraints on the keys

[David Feuer]

The instances won't be orphans if they're in the same module as the class
definition.

On Fri, Sep 7, 2018, 2:12 PM waldmann <johannes.waldmann at htwk-leipzig.de>
wrote:

> On 09/07/2018 05:51 PM, David Feuer wrote:
>
> > class e ~ Elem s => SetC e s where
>
> OK. At the use site, under both proposals,
> there'll be a two argument constraint.
> In my version, the second argument was curried away.
>
> One way or the other - why don't we?
> What could be the downsides here?
>
> I guess since it's meant to sit atop (some) modules
> from various packages (containers, unordered-containers, enummapset)
> it's best to release it as a separate package,
> containing the classes, and orphan instances.
>
> - J.
>
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