Hello, The discussion on the libraries list is archived here: http://www.haskell.org/pipermail/libraries/2011-September/016699.html
There hasn't been a corresponding discussion for Haskell Prime so, technically, GHC deviates from the standard. -Iavor On Fri, Dec 23, 2011 at 9:41 AM, Simon Peyton-Jones <simo...@microsoft.com> wrote: > I'm confused too. I'd welcome clarification from the Haskell Prime folk. > > S > > -----Original Message----- > From: Serge D. Mechveliani [mailto:mech...@botik.ru] > Sent: 23 December 2011 17:36 > To: Simon Peyton-Jones > Subject: Re: 7.4.1-pre: Show & Integral > > On Thu, Dec 22, 2011 at 08:14:54PM +0000, Simon Peyton-Jones wrote: >> | 2011/12/22 Edward Kmett <ekm...@gmail.com>: >> | > The change, however, was a deliberate _break_ with the standard that >> | > passed through the library review process a few months ago, and is now >> | > making its way out into the wild. >> | >> | Is it reasonable to enquire how many standard-compliant implementations >> | of Haskell there are? >> >> Just to be clear, the change IS the standard. GHC has to change to be >> compliant. >> At least that's how I understand it. > > > I am confused. > I am looking now at the on-line specification of Haskell-2010, > 6.3 Standard Haskell Classes. > It shows that Integral includes Show: > > Eq Show > \ / > Num > | > Enum Real > \ | > Integral > > This is also visible in the further standard class declarations in this > chapter. > > Hence, for `x :: Integral a => a' it is correct to write (shows x ""). > And ghc-7.4.0.20111219 does not allow this. > So, ghc-7.4.0.20111219 breaks the 2010 standard. Now, Edward Kmett writes > that > this break is done deliberately. > > Am I missing something? > > I witness this for the first time: that GHC deliberately breaks the current > Haskell standard. > Probably, many people (as myself) dislike this point of the standard. > Well, they can write a dummy Show implementation for their type T: > showsPrec _ _ = showString "(<t> :: T)", > > and wait for an improved standard, say, Haskell-II > -- ? > > Regards, > > ------ > Sergei > mech...@botik.ru > > > > > > > _______________________________________________ > Haskell-prime mailing list > Haskell-prime@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-prime _______________________________________________ Haskell-prime mailing list Haskell-prime@haskell.org http://www.haskell.org/mailman/listinfo/haskell-prime