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

MigMit miguelimo38 at yandex.ru
Sat Aug 8 21:17:15 UTC 2015


I won't say that's a legitimate concern. Representation doesn't matter here; if those two were indistinguishable (by Haskell code, without "hacks"), then the fact that they are represented differently would be irrelevant. But they ARE distinguishable, by a perfectly normal Haskell code.

> On 08 Aug 2015, at 23:13, Brandon Allbery <allbery.b at gmail.com> 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?
> 
> -- 
> brandon s allbery kf8nh                               sine nomine associates
> allbery.b at gmail.com                                  ballbery at sinenomine.net
> unix, openafs, kerberos, infrastructure, xmonad        http://sinenomine.net
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