Note that there's another dimension to this question: whether this pragma is switched on by default. We already have precedents like NondecreasingIndentation.
So, if you mean heavy-weigth to use, not to implement, then this may address your concern. Now, with my haskell-src-exts maintainer hat on, things like this tend to be problematic for us, because users assume that if ghc compiles a program without any pragmas, so should HSE, which it currently doesn't. Perhaps we should try to replicate GHC's default behavior in terms of the default accepted language, too. But as a GHC user, I agree that this extension is innocent enough to be turned on by default. Still, Haskell 98 and Haskell 2010 should remain immutable, in my opinion. PS I just remembered that newer Cabals ask you to specify either Haskell98 or Haskell2010, so that might make a turned-on-by-default extension less useful and more confusing. On 23/09/14 11:03, Johan Tibell wrote: > I must say that requiring a language pragma makes the feature quite a bit > more heavy weight. We're not changing the meaning of any existing programs, > just allowing some new ones. One could argue that perhaps the HaskellXX > standard might pick up this new pragma and thus making it unnecessary > eventually, but the standardization process is dead (and even when it was > alive, it was lagging actual practice enough that it was largely ignored.) > > > On Tue, Sep 23, 2014 at 9:41 AM, Roman Cheplyaka <r...@ro-che.info> wrote: > >> 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 >> >> > _______________________________________________ ghc-devs mailing list ghc-devs@haskell.org http://www.haskell.org/mailman/listinfo/ghc-devs
