Proposal: Add singleton function to Data.List module

[Andrew Lelechenko]

> - `pure`: Polymorphic, works for any `Functor`.

It is OK to have polymorphic folds and length, so what is wrong with pure? 

Adding singleton to Data.List is a breaking change, when Data.Map.singleton was exported unqualified. 
And there is no singleton in Data.List.NonEmpty as well. 

-1 from me.

Best regards,
Andrew

> On 12 Aug 2019, at 19:36, Brent Yorgey <byorgey at gmail.com> wrote:
> 
> At the risk of completely derailing the conversation, I have always called this the "robot monkey operator".  I fail to see what is so ninja-like about it.
> 
> Anyway, I think I am +1 on adding Data.List.singleton.
> 
> -Brent
> 
> On Mon, Aug 12, 2019, 12:35 PM Zemyla <zemyla at gmail.com <mailto:zemyla at gmail.com>> wrote:
> I also like the ninja-robot operator, because it's visually
> interesting and easy to search for.
> 
> Also, if you're importing several libraries which already use
> "singleton", then you have to use "List.singleton" every time, which
> is far uglier to me.
> 
> On Mon, Aug 12, 2019 at 12:03 PM Herbert Valerio Riedel
> <hvriedel at gmail.com <mailto:hvriedel at gmail.com>> wrote:
> >
> > > - `(:[])`: Subjectively ugly.
> >
> > I consider "subjectively ugly" to be a non-technical and thus really
> > weak argument to dismiss the list-idiomatic ninja-robot-operator (:[])
> > which also happens to be shorter than the proposed alias for it. I for
> > one don't see a significant benefit for adding a redundant synonym to
> > `Data.List` and are thus -1 on this.
> >
> > > singleton :: a -> [a]
> > > singleton x = [x]
> > _______________________________________________
> > Libraries mailing list
> > Libraries at haskell.org <mailto:Libraries at haskell.org>
> > http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries <http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries>
> _______________________________________________
> Libraries mailing list
> Libraries at haskell.org <mailto:Libraries at haskell.org>
> http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries <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/20190812/196de467/attachment.html>