un-used record wildcards

[Simon Peyton-Jones]

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-bounces at haskell.org [mailto:glasgow-haskell-users-
|  bounces at haskell.org] On Behalf Of Serge D. Mechveliani
|  Sent: 14 October 2010 11:01
|  To: Antoine Latter
|  Cc: glasgow-haskell-users at 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 <mechvel at 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.
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