[Haskell-cafe] an idea for modifiyng data/newtype syntax: use `::=` instead of `=`

[Tom Ellis]

On Sat, Aug 08, 2015 at 05:20:00PM -0400, Brandon Allbery wrote:
> On Sat, Aug 8, 2015 at 5:16 PM, Tom Ellis <
> tom-lists-haskell-cafe-2013 at jaguarpaw.co.uk> wrote:
> > On Sat, Aug 08, 2015 at 05:13:30PM -0400, Brandon Allbery wrote:
> > > On Sat, Aug 8, 2015 at 5:11 PM, Tom Ellis <
> > > tom-lists-haskell-cafe-2013 at jaguarpaw.co.uk> wrote:
> > >
> > > > No, not at all.  I'm making a much stronger claim than that.  I'm
> > claiming
> > > > the functionality provided by newtype is completely subsumed by that
> > > > provided by data.
> > >
> > > When did `data` start guaranteeing that the representation of a single
> > > constructor, strict `data' wrapper around another type is exactly the
> > same
> > > as the wrapped type?
> >
> > I make no claims about the operational semantics of existing compilers, but
> > can you point out a reason why data of a single strict field *shuoldn't* be
> > compiled in the same way as a newtype?
> 
> Because it's a bizarre special case compared to the way `data` works for
> everything else?
> 
> Also, the behavior I described is not something that can just be ignored as
> an optimization in a particular compiler. It is part of the language
> specification. In fact, it is the *primary reason* for the existence of
> `newtype`.

I'm not really sure what we're debating here.  I merely pointed out that a
language with strict data fields has no less functionality than one that
adds newtype.  I'm not making any proposal, I'm just making an observation
that some may find interesting.

Tom