"Class Aliases"

NumberStuff.hs

module NumberStuff where

import qualified Prelude

class CanAdd a where
	(+) :: a -> a -> a

class CanNegate a where
	negate :: a -> a

class FromInteger a where
	fromInteger :: Prelude.Integer -> a

class (CanAdd a, CanNegate a, FromInteger a) => Num a

instance CanAdd Prelude.Integer where
	(+) = (Prelude.+)

instance CanNegate Prelude.Integer where
	negate = Prelude.negate

instance FromInteger Prelude.Integer where
	fromInteger = Prelude.id

instance Num Prelude.Integer

someFunc :: (Num a) => a -> a
someFunc x = negate (x + x + fromInteger 12)