ANNOUNCE: GHC 6.8.3 Release Candidate
dons at galois.com
Sun Jun 1 16:46:43 EDT 2008
I was looking at the cabal file used to build docon,
I note the current flags are:
+RTS -M400m -RTS
Do you gain any performance benefit using:
-O2 -fvia-C -optc-O2
Also, would you be interested in releasing the cabal bundle for docon on
hackage.haskell.org , so it can be easily installed by others?
> On Sun, Jun 01, 2008 at 01:13:06AM +0100, Ian Lynagh wrote:
> > Hi Serge,
> > On Sat, May 31, 2008 at 12:54:50PM +0400, Serge D. Mechveliani wrote:
> > > This is a bug report for the ghc candidate of May 27, 2008
> > > for ghc-6.8.3.
> > > A short program example for this bug candidate is on
> > >
> > > http://botik.ru/pub/local/Mechveliani/ghcBugs/candidateMay27-08-bug.zip
> > Thanks, I've finally tracked this down. The problem is that when you
> > evaluate something like
> > f ^ 10
> > in 6.8.2 the result was
> > res
> > while in 6.8.3 it is
> > 1 * res
> > I think this is actually a bug in your class instances, but I will try
> > to look at http://hackage.haskell.org/trac/ghc/ticket/2306 before 6.8.3
> > which should, as a side-effect, make it work again.
> Probably, 6.8.3 is wrong.
> Because when res :: Num a => a, 1*res means
> ((fromInteger 1) :: a) * res
> in Haskell-98. Right?
> And (fromInteger n) :: a can be defined arbitrarily by the programmer.
> For example, DoCon has the instance
> instance CommutativeRing a => Num (Pol a)
> fromInteger _ = error "No (fromInteger n) :: Pol _ !\
> \Apply instead fromi <samplePolynomial> n."
> -- something of this kind.
> This is why res and 1*res are not equivalent in Haskell-98 for
> res :: Num a => a.
> Am I missing something?
> Serge Mechveliani
> mechvel at botik.ru
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