[Haskell-cafe] Inheritance without OOHaskell

[Georg Martius]

Hi,

I would like to add some minor improvement on usability of the existential 
type Connection proposed by Bulat.
> data Connection = forall c . (IsConnection c) => Conn c
 The thing is that you usually have functions like
send :: (isConnection c) => c -> String -> IO()
or whatever. In order to be able to feed a variable of type Connection into 
functions like send it is handy to define

instance IsConnection Connection where
	foo (Conn c) = foo c
	setFoo bar (Conn c) = Conn $ setFoo bar c
	...

which delegates functions "into" the item inside the exitential wrapper.

Cheers,
	Georg
-- 
---- Georg Martius,  Tel: (+49 34297) 89434 ----
------- http://www.flexman.homeip.net ---------
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