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

[Joseph Abrahamson]

This one draws me out of silence. Strong +1 on (<$>). 0 on (<$).

—
Sent from Mailbox

On Tue, Feb 24, 2015 at 11:08 AM, Alois Cochard <alois.cochard at gmail.com>
wrote:

> It is clearly sad that we reached that stage before realizing the problem,
> but OTOH it would be worst to not fix it now that we still have a (very)
> last chance.
> +1 on both from me.
> Unlike Greg I don't think encouraging people to use the QuasiQuoter is a
> good idea, it's for me obvious that the <$> syntax is widely used, I see it
> in mostly every open source code I read.
> On 24 February 2015 at 17:03, Richard Eisenberg <eir at cis.upenn.edu> wrote:
>> This is a tough call for me.
>>
>> This change will be very annoying, I think. When updating for 7.10, I was
>> quite surprised that I still needed to import Control.Applicative for <$>,
>> and put in the CPP to do so. Now I'll have to remove that from quite a few
>> modules. Given that we plan only a week for RC3, there are a lot of modules
>> in the ecosystem that will have to be updated within that week!
>>
>> Of course, an author who doesn't update (by removing the now-redundant
>> import of <$>) just gets a warning, but it's still annoying.
>>
>> In my opinion, little changes like this, made right before the deadline,
>> make Haskell feel more like a little research language than something meant
>> to support industrial work.
>>
>> All that said, I desperately miss having <$> in the Prelude in 7.10. Hence
>> the tough call.
>>
>> 0 from me, then.
>>
>> Richard
>>
>> On Feb 24, 2015, at 10:47 AM, Christopher Reichert <creichert07 at gmail.com>
>> wrote:
>>
>> >
>> > +1 on <$>. Indifferent on <$.
>> >
>> > -Christopher
>> >
>> > On Tue, Feb 24 2015, 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
>> >
>> > --
>> > Christopher Reichert
>> > irc: creichert
>> > gpg: C81D 18C8 862A 3618 1376  FFA5 6BFC A992 9955 929B
>> > _______________________________________________
>> > 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
>>
> -- 
> *Λ\ois*
> http://twitter.com/aloiscochard
> http://github.com/aloiscochard
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.haskell.org/pipermail/libraries/attachments/20150224/dd6101c5/attachment.html>