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

[Greg Fitzgerald]

-1 on both.  Leaving them out might encourage people to use "pure foo"
or the idiom QuasiQuoter.  It's not obvious [to me at least] which of
the 3 styles is best, so I'd prefer to keep the additional syntax out
of the Prelude.

-Greg

On Tue, Feb 24, 2015 at 7:43 AM, Alec <alec at deviant-logic.net> wrote:
> +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
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