GHC support for the new "record" package

[Nikita Volkov]

Chris, this is great! Looks like we can even get rid of the Rec prefix!

   -

   A phrase in round braces and with :: is itself unambiguous in the type
   context.
    -

   A phrase in round braces with = symbols is unambiguous in the expression
   context.

Concerning the pattern context a solution needs to be found though. But the
two points above are enough for me to fall in love with this direction! The
{| braces had a too icky of a touch to them and the plain { required the
user to choose whether to use the standard record syntax or anonymous one
on the module scale, but not both.
​


2015-01-29 0:26 GMT+03:00 Christopher Done <chrisdone at gmail.com>:

> There’s too much to absorb in this discussion at the moment and I’m
> late to the party anyway, but I would like to make a small note on
> syntax. Given that this is very similar to TRex both in behaviour and
> syntactic means of construction, why not just take TRex’s actual
> syntax? http://en.wikipedia.org/wiki/Hugs#Extensible_records
>
> type Point2D = Rec (x::Coord, y::Coord)
> point2D = (x=1, y=1) :: Point2D
> (#x point)
>
> It seems like it wouldn’t create any syntactical ambiguities (which is
> probably why the Hugs developers chose it).
>
> Ciao
>
> On 20 January 2015 at 22:44, Simon Marlow <marlowsd at gmail.com> wrote:
> > For those who haven't seen this, Nikita Volkov proposed a new approach to
> > anonymous records, which can be found in the "record" package on Hackage:
> > http://hackage.haskell.org/package/record
> >
> > It had a *lot* of attention on Reddit:
> > http://nikita-volkov.github.io/record/
> >
> > Now, the solution is very nice and lightweight, but because it is
> > implemented outside GHC it relies on quasi-quotation (amazing that it
> can be
> > done at all!).  It has some limitations because it needs to parse Haskell
> > syntax, and Haskell is big.  So we could make this a lot smoother, both
> for
> > the implementation and the user, by directly supporting anonymous record
> > syntax in GHC.  Obviously we'd have to move the library code into base
> too.
> >
> > This message is by way of kicking off the discussion, since nobody else
> > seems to have done so yet.  Can we agree that this is the right thing and
> > should be directly supported by GHC?  At this point we'd be aiming for
> 7.12.
> >
> > Who is interested in working on this?  Nikita?
> >
> > There are various design decisions to think about.  For example, when the
> > quasi-quote brackets are removed, the syntax will conflict with the
> existing
> > record syntax.  The syntax ends up being similar to Simon's 2003 proposal
> >
> http://research.microsoft.com/en-us/um/people/simonpj/Haskell/records.html
> > (there are major differences though, notably the use of lenses for
> selection
> > and update).
> >
> > I created a template wiki page:
> > https://ghc.haskell.org/trac/ghc/wiki/Records/Volkov
> >
> > Cheers,
> > Simon
> > _______________________________________________
> > ghc-devs mailing list
> > ghc-devs at haskell.org
> > http://www.haskell.org/mailman/listinfo/ghc-devs
>
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