It's completely lawless and there's no semantically meaningful or unique "default" value for most types. It's much better practice to use explicit default values declared by name and imported explicitly. Data.Default is probably one of the most notorious abuses of type classes in the ecosystem. I'm aware it's common, I'd just hoped people would've started trimming it away. Consider Monoid. What's the default value for `Int`? Should it be the identity? The zero? For which operations over `Int`? A "default" value should either be something explicitly created and defined as a value for a domain-specific purpose or it should have a specific meaning with respect to an operation defined by a law such as w/ the monoids of summation and multiplication. On Tue, May 8, 2018 at 4:10 AM, Marco Zocca <zocca.marco@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 ?
On Tue, May 8, 2018 at 11:02 AM, Christopher Allen <cma@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@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@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries
-- Chris Allen Currently working on http://haskellbook.com
-- Chris Allen Currently working on http://haskellbook.com