Thu, 3 May 2001 02:54:26 EDT, [EMAIL PROTECTED] <[EMAIL PROTECTED]> pisze:
> class Shape a where
> getx :: a -> Int
> setx :: a -> Int -> a
>
> data ExistentialShape =
> forall a. Shape a => MakeExistentialShape a
>
> instance Shape ExistentialShape where
> getx (MakeExistentialShape a) = getx a
> setx (MakeExistentialShape a) newx = setx a newx
Should be:
setx (MakeExistentialShape a) newx = MakeExistentialShape (setx a newx)
The result of setx must have the same type as its first argument.
--
__("< Marcin Kowalczyk * [EMAIL PROTECTED] http://qrczak.ids.net.pl/
\__/
^^ SYGNATURA ZASTĘPCZA
QRCZAK
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