Ivan,
IT> Stefan Holdermans wrote:
IT>
IT> Huh. I'm really get stuck. Can someone write me working
IT> implementation of my crap?
Huh? Did *I* wrote that ... ? ;)
\begin{code}
{-# -OPTIONS -fglasgow-exts #-}
class Location a where
point :: a -> String
class (Location b) => Packet a b where
source :: a -> b
destination :: a -> b
size :: forall c . (Num c) => a -> c
data TestLocation = TestSource | TestDestination
deriving (Show)
instance Location TestLocation where
point = show
data TestPacket = TestPacket
instance Packet TestPacket TestLocation where
source = const TestSource
destination = const TestDestination
size = const 99
main :: IO ()
main = print $ (source TestPacket :: TestLocation)
\end{code}
As I mentioned, depending on your needs, there are other options: enriching
the Location class, parameterizing the packet types, ...
HTH,
Stefan
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