[PROPOSAL] Adding Generics-based DefaultSignature to `deepseq` package

[Andreas Abel]

I am +1 on this change.  I was naively under the wrong impression that a 
simple

   instance NFData Bla

is enough already with the current package.  I would be nice if it 
worked, and the proposal seems to achieve this (at least if one derives 
Generic).

--Andreas

On 16.10.2014 21:41, Edward Kmett wrote:
> On one hand, the change is a path to a better deepseq that is more correct.
>
> On the other hand
>
> 1.) It does change the semantics of existing code.
>
> 2.) It does cause existing code that works to break if they don't supply
> a Generic instance or a manual default.
>
> Admittedly:
>
> #1 happens by making it more strict, which is what we want in the case
> of NFData, for once.
> #2 is something that is easily rectified and makes the resulting code
> more robust/useful anyways. Folks who don't want to lean on generics
> have the option to just write the rnf x = seq x ()default, so nobody is
> being forced to lean on the extension.
>
> I'm somewhat on the fence about this, because I don't like silent
> semantics changes, but as it is only happening by making things more
> strict /in the one place in the language/ where that is the very point,
> you can consider me weakly +1.
>
> -Edward
>
>
> On Thu, Oct 16, 2014 at 1:09 PM, Andres Löh <andres.loeh at gmail.com
> <mailto:andres.loeh at gmail.com>> wrote:
>
>     > The Proposal
>     > ============
>     >
>     > I hereby propose to merge `deepseq-generics`[2] into `deepseq`[1] in
>     > order to add Generics support to the `NFData` class based on the
>     > `-XDeriveGenerics` and `-XDefaultSignature` language extensions.
>     >
>     > A concrete patch is available for bike-review at [3]
>
>     +1
>
>     Cheers,
>        Andres
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-- 
Andreas Abel  <><      Du bist der geliebte Mensch.

Department of Computer Science and Engineering
Chalmers and Gothenburg University, Sweden

andreas.abel at gu.se
http://www2.tcs.ifi.lmu.de/~abel/