Bug in deriving Data Typeable?
José Pedro Magalhães
jpm at cs.uu.nl
Fri Mar 13 04:49:30 EDT 2009
On Thu, Mar 12, 2009 at 17:02, Bernd Brassel <bbr at informatik.uni-kiel.de>wrote:
> José Pedro Magalhães wrote:
> > Hi Bernd,
> > I guess this might be the same issue reported some time ago (
> > http://thread.gmane.org/gmane.comp.lang.haskell.generics/53/focus=54):
> > derived instances of Data do not define dataCast1. If you define your own
> > instance of Data for MyMaybe and add the definition of dataCast1 you will
> > get the expected behavior.
> Your link pointed me in the right direction to fix the bug for my
> application. Many thanks! Did you submit a bug report?
Now I did: http://hackage.haskell.org/trac/ghc/ticket/3087
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