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

[Alois Cochard]

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/20150224/62fd1a87/attachment-0001.html>