Permitting trailing commas for record syntax ADT declarations

[Roman Cheplyaka]

On 23/09/14 10:11, Alexander Berntsen wrote:
> On 22/09/14 21:07, Simon Peyton Jones wrote:
>> have a language extension TrailingCommas (or something) to enable
>> the extension
> For clarification: are you overruling the "do we sneak it in HEAD or
> use pragma(s)"-vote and telling me to do the latter?
> 
> If we can sneak it into HEAD (this is @ you Johan, too), I suggest
> that someone applies my patches to make import and export lists
> support leading commas (presently they only support trailing commas,
> per the report) -- and following this I can just send a bunch of
> "Permit leading/trailing ',' in Foo" patches to Phabricator, and you
> guys can bikeshed over there about which ones you actually want to
> commit. ;-)
> 
> If I am to go down the pragma route, I guess I can make a
> RudundantCommas pragma or something like that, that implements
> trailing commas for imports/exports, and leading/trailing commas for
> the suggestions in this thread.
> 
> I'm +1 on the GHC HEAD route, but I'm not exactly violently opposed to
> the pragma route either.

Here's my reasoning:

If you invoke ghc with -XHaskell2010, then trailing commas shouldn't be
accepted, because they do not belong to Haskell 2010.

Which means that you do need an extension to identify this difference in
behavior.

Roman

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 819 bytes
Desc: OpenPGP digital signature
URL: <http://www.haskell.org/pipermail/ghc-devs/attachments/20140923/ca5952b4/attachment.sig>