Proposal: Add (<$>) to Prelude as part of the AMP in GHC 7.10-RC3

Alec alec at deviant-logic.net
Tue Feb 24 15:43:36 UTC 2015


+1 on both

On Tue Feb 24 2015 at 10:42:41 AM Michael Snoyman <michael at snoyman.com>
wrote:

> +1 on <$>
> +1 on <$
>
> On Tue Feb 24 2015 at 5:39:56 PM Edward Kmett <ekmett at gmail.com> wrote:
>
>> We have a couple of weeks until the third release candidate for GHC 7.10
>> goes out the door.
>>
>> Along the way with the last couple of release candidates folks have found
>> some problems with the way we implemented the AMP. [1][2]
>>
>> Most notably, we failed to include (<$>) in the Prelude, so the standard
>> idiom of
>>
>> foo <$> bar <*> baz <*> quux
>>
>> doesn't work out of the box!
>>
>> I'd like to include (<$>) in the Prelude in RC3.
>>
>> I'd also like to invite discussion about whether folks believe we should
>> include (<$) out of the box.
>>
>> (<$) has been a member of Functor for a long time, which is only visible
>> if you import it from Data.Functor or bring in Control.Applicative. There
>> is an idiom that you use (<*) and (<$) to point to the parts of the
>> structure that you want to keep the answers from when building longer such
>> Applicative chains.
>>
>> Discussion Period: 2 weeks
>>
>> Thank you,
>> -Edward Kmett
>>
>> [1]
>> http://www.reddit.com/r/haskell/comments/2wzixa/shouldnt_be_in_prelude/
>> [2] https://plus.google.com/115504368969270249241/posts/URzeDWd7qMp
>> _______________________________________________
>> Libraries mailing list
>> Libraries at haskell.org
>> http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries
>>
> _______________________________________________
> Libraries mailing list
> Libraries at haskell.org
> http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.haskell.org/pipermail/libraries/attachments/20150224/70e18413/attachment-0001.html>


More information about the Libraries mailing list