I think the technique described at
http://haskell.org/haskellwiki/GHC/AdvancedOverlap
may give you what you want. I've never tried it myself though.
/ Emil
Tobias Bexelius skrev:
Yeah, I realized that.
But heres where I would like the undecidable incoherent instances to kick in,
i.e. as long as I haven't got any NumVec instances GHC should be able to choose
only one of the Mult instances. Or do I have too much faith in the
-fallow-incoherent-instances flag now? :/
I would like to be able to write something like
instance (Vec a x, -Num (a x)) => Mult (a x) (a x) x where (*.) = dot
where -Num (a x) means that (a x) must not be an instance of Num. Can I express
this in some way?
Regards
Tobias
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