The actual problem is quite similar to the one that I provided or to the one in the description of the proposed extension that you linked. Someone on another forum suggested record functions but I'm not sure I understood correctly how that would work around this problem. Any suggestion is greatly appreciated! Thanks, -Gabor Martijn van Steenbergen-2 wrote:
siki wrote:
I'm not sure if this is possible at all. I'd like to do something like this:
class A a where foo :: a -> Double
foo a = 5.0
class (A a) => B a where foo a = 7.0
This is currently not possible in Haskell. It's been proposed, though:
http://haskell.org/haskellwiki/Class_system_extension_proposal
If you have an actual example we might be able to come up with a different way of modelling it so that it does what you want, though.
Martijn.
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