[Hugs-users] Record puns, time for removal?

[Iavor Diatchki]

Hello,
I think the "it may be confusing to novices" argument tends to be
over-used and we should be careful before we make language decisions
solely based on it.  At the  very least, when there is a suggestion
that something might be confusing to someone, there should be an
explanation of what/why/to whom it is confusing.

I think record puns are a nice feature, it is easy to explain, and
without them the Haskell record system is less useful, at least to me.

By the way, if I recall correctly, in Johan Nordlander's O'Hugs the ..
notation (called record packing, I think) could also be used to create
record values.  I think it worked like this:
> data Point = Point { x,y :: Int }
> pt = let { x = 3; y = 4 } in Point { .. }

The ".." is expanded to "{x = x, y = y}" based on the fields for the
particular constructor.  It seems that if we have the "Point { .. }"
pattern, we should also have the constructor version.  What do people
think?

-Iavor




On 10/31/06, Seth Kurtzberg <seth at cql.com> wrote:
> On Tue, 31 Oct 2006 13:59:45 +0300
> Bulat Ziganshin <bulat.ziganshin at gmail.com> wrote:
>
> > Hello Neil,
> >
> > Tuesday, October 31, 2006, 4:04:23 AM, you wrote:
> >
> > >> > puns like Foo { .. } would be great too.
> > >>
> > >> I'd vote for enabling them with a command line switch, rather than by default, as they can be confusing to folks learning the language.
> >
> > > How discussions come full circle :) I started this discussion on the
> > > Hugs users list because I want to _remove_ the command line switch for
> > > puns from Yhc. I'm not overly fussed whether I remove the entire
> > > feature, or just remove the command line and make it always on by
> > > default, but I do want the command line switch gone!
> >
> > compiler switch can't be made a part of Haskell' :)
> >
> > and anyway, i don't see how cmdline switch may help noivices - when
> > they use ".." by mistake and program mysteriously not fails? or when
> > they stare at the other's program and understand that this unknown
> > ".." work only because this program compiled with some special switch?
>
> I wasn't talking about the .., I was talking about the primary issue raised by the email, which has nothing to do with ..
>
> Instead of assuming that I was saying something totally useless and worthless, it might not be a bad idea to respond to _my_ email, not an email which contains a quote of one line from my email.
>
> >
> > and yes, record puns seems very ggod candidate for H'. it's widely
> > used (i used it until switched to GHC), it was already in Haskell, and
> > now it is impelemnted by every compiler
> >
> > wildcard puns is more discussible, but i personally need this feature
> >
> >
> > --
> > Best regards,
> >  Bulat                            mailto:Bulat.Ziganshin at gmail.com
> >
> >
> _______________________________________________
> Glasgow-haskell-users mailing list
> Glasgow-haskell-users at haskell.org
> http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
>