Hi Simon, I've seen this issue with GHC 6.12.3 (and assumed it was by design). It occurs with a slight modification of your example:
{-# LANGUAGE RecordWildCards #-} module Test where data T = MkT { f,g :: Int } p x = let MkT{..} = x in f This example warns about "Defined but not used: `g'" on the line defining p. I've raised a GHC bug: http://hackage.haskell.org/trac/ghc/ticket/4411 about this warning. Thanks, Neil > Which version of GHC are you using? GHC 6.12 does not complain about unused > variables bound by "..". Try this, which complains about y, but not g. > > Simon > > {-# LANGUAGE RecordWildCards #-} > module Test where > > data T = MkT { f,g :: Int } > > p (MkT { .. }) y = f > > > | -----Original Message----- > | From: glasgow-haskell-users-boun...@haskell.org > [mailto:glasgow-haskell-users- > | boun...@haskell.org] On Behalf Of Serge D. Mechveliani > | Sent: 14 October 2010 11:01 > | To: Antoine Latter > | Cc: glasgow-haskell-users@haskell.org > | Subject: Re: un-used record wildcards > | > | On Wed, Oct 13, 2010 at 01:47:11PM -0500, Antoine Latter wrote: > | > On Wed, Oct 13, 2010 at 1:02 PM, Serge D. Mechveliani <mech...@botik.ru> > | wrote: > | > > Dear GHC developers, > | > > > | > > I use the language extension of RecordWildcards, for example, > | > > f (Foo {foo1 = n, foo2 = m, ..}) = ... > | > > > | > > But the complier warns about un-used values of foo3, foo4, > | > > probably, due to the extension of > | > > Foo {foo1 = n, foo2 = m, foo3 = foo3, foo4 = foo4}. > | > > > | > > In such cases, these warnings look as unneeded. > | > > Is it possible to have an un-used binding warnings with exception for > | > > wildcards in records? > | > > If not, then has it sense to introduce an option? > | > > > | > > | > If you're not using foo3 and foo4, can you not put it the ellipsis? > | > that won't cover every case (such as where you're using foo3 but not > | > foo4). > | > > | > Antoine > | > > | > | Indeed, thank you. > | It occurs that under RecordWildcards the compiler allows to skip some > | record fields in a pattern. > | _______________________________________________ > | Glasgow-haskell-users mailing list > | glasgow-haskell-us...@haskell.org > | http://www.haskell.org/mailman/listinfo/glasgow-haskell-users > > _______________________________________________ > Glasgow-haskell-users mailing list > Glasgow-haskell-users@haskell.org > http://www.haskell.org/mailman/listinfo/glasgow-haskell-users > _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users