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data Foo = Foo { alpha :: Int, beta :: Int, gamma :: Int | |
, delta :: Int, eta :: Int } deriving (Eq, Ord, Show) | |
plusOn :: Num a => (Foo -> a) -> Foo -> Foo -> a | |
plusOn = on (+) | |
maxOn :: Ord a => (Foo -> a) -> Foo -> Foo -> a | |
maxOn = on max | |
newtype AddFoo = AddFoo { getAddFoo :: Foo } | |
instance Semigroup AddFoo where | |
AddFoo x <> AddFoo y = | |
AddFoo $ Foo (plusOn alpha x y) (maxOn beta x y) (plusOn gamma x y) | |
(maxOn delta x y) (plusOn eta x y) | |
instance Monoid AddFoo where | |
mempty = AddFoo (Foo 0 0 0 0 0) | |
mappend = (<>) | |
newtype MaxFoo = MaxFoo { getMaxFoo :: Foo } | |
instance Semigroup MaxFoo where | |
MaxFoo x <> MaxFoo y = | |
MaxFoo $ Foo (maxOn alpha x y) (maxOn beta x y) (maxOn gamma x y) | |
(maxOn delta x y) (maxOn eta x y) | |
instance Monoid MaxFoo where | |
mempty = MaxFoo (Foo 0 0 0 0 0) | |
mappend = (<>) |
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