[Haskell-cafe] Overloading in a sub-class

Patrick Browne patrick.browne at dit.ie
Wed Aug 17 18:10:22 CEST 2011

Below are two questions concerning overloading in a sub-class.

class Numb0 a where
 (+) :: a -> a -> a
 negate :: a -> a

instance Numb0 Int where
 x + y = y
 negate x = x

-- Are  + and negate part of the signature of Numb1?
class Numb0 a  => Numb1 a where

-- Is it possible to override these operations in instances of Numb1?
-- Something like:
-- instance Numb1 Float where
--    x + y = y
--    negate x =  x
-- Or even using Int as in the super class instance:
-- instance Numb1 Int where
--    x + y = y
--    negate x =  x

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