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v0d1ch/lenses.hs

Forked from dminuoso/lenses.hs
Created February 22, 2019 11:36
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lenses.hs
traverseX :: forall f. Functor f = (a -> f a) -> Vec3 a -> f (Vec3 a)
traverseX f (Vec3 x y z) = (\h -> Vec3 h) <$> f x
traverseY :: forall f. Functor f = (a -> f a) -> Vec3 a -> f (Vec3 a)
traverseY f (Vec3 x y z) = (\h -> Vec3 h) <$> f x
traverseZ :: forall f. Functor f = (a -> f a) -> Vec3 a -> f (Vec3 a)
traverseZ f (Vec3 x y z) = (\h -> Vec3 h) <$> f x
type Lens s a = forall f. Funtor f => (a -> f a) -> s -> f s
_X :: Lens a (Vec3 a)
_X = traverseX
_Y :: Lens a (Vec3 a)
_Y = traverseY
_Z :: Lens a (Vec3 a)
_Z = traverseZ
-- > over _X (+1) (Vec3 1 0 7)
-- this is just for visual prettification, its just "flipped application"
(&) = flip ($)
(%~) = over
-- We can use it like this
-- > (Vec3 1 0 7) & _X %~ (+1)
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