rfc: include bimap into Data.Either

Andreas Abel andreas.abel at ifi.lmu.de
Sun Apr 20 12:29:03 UTC 2014


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On 20.04.2014 07:16, João Cristóvão wrote:
>> given arrowchoice, i withdraw my proposal. thank you for pointing
>> me
> there.
> 
> Please don't.

+1

Stuff like this belongs in Data.Either, not in Control.Arrow.  We had
the same issue for Data.Tuple vs. Control.Arrow a while ago.

> While I agree that duplication is undesirable, I urge you all to 
> consider the begginers and even intermediate haskeller point of
> view.
> 
> A search on hoogle will reveal nothing. A search on hayoo will
> reveal Data.Either.Combinators, but most users are not even aware
> of hoogle.
> 
> They will probably just google either and end up in Data.Either.
> 
> In Data.Either there is _absolutely_ no way to reach the Arrow
> combinators. And even if the user somewhat finds Arrows, in an
> unrelated search, he will also not see the Either use case.
> 
> I would even argue that the Arrow abstraction is something that is
> in a totally different level than such a simple type as Either, and
> most haskellers will only use (arrows) much further ahead, but I
> agree this is highly arguable.
> 
> So:
>> It may be worth adding documentation to Arrow about what they
>> mean
> 
> Not only to arrows, please: this documentation is needed _on 
> Data.Either_, which is where most users, I believe, would search
> for such a funcion.
> 
> Thanks João
> 
> 
> 2014-04-19 15:50 GMT+01:00 Edward Kmett <ekmett at gmail.com 
> <mailto:ekmett at gmail.com>>:
> 
> -1 from me for the reason Herbert already stated: They are 
> generalized by existing combinators already in base.
> 
> It may be worth adding documentation to Arrow about what they
> mean, but that of course doesn't help users trying to find them via
> hoogle.
> 
> -Edward
> 
> 
> On Sat, Apr 19, 2014 at 7:06 AM, Tobias Florek <haskell at ibotty.net 
> <mailto:haskell at ibotty.net>> wrote:
> 
> You may turn it into a proposal for Hoogle. :-) For the type of
> mapLeft Hoogle lists only irrelevant results on the first page and 
> for the type of bimap it does not list a result, at all.
> 
> 
> yeah i checked there. unfortunately it's not as easy to improve 
> hoogle...
> 
> regards, tobias florek
> 
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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/
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