Hello Serge, I was looking at the cabal file used to build docon, I note the current flags are: ghc-options: -fglasgow-exts -fallow-overlapping-instances -fallow-undecidable-instances -fno-warn-overlapping-patterns -fwarn-unused-binds -fwarn-unused-matches -fwarn-unused-imports -O +RTS -M400m -RTS Do you gain any performance benefit using: -O2 -fvia-C -optc-O2 I'm wondering. Also, would you be interested in releasing the cabal bundle for docon on hackage.haskell.org , so it can be easily installed by others? -- Don mechvel:
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) where ... 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@botik.ru _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users