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lens Control.Lens.Combinators This generalizes mapAccumR to an arbitrary Traversal.
mapAccumR ≡ mapAccumROf traverse
mapAccumROf accumulates State from right to left.mapAccumROf :: Iso s t a b -> (acc -> a -> (acc, b)) -> acc -> s -> (acc, t) mapAccumROf :: Lens s t a b -> (acc -> a -> (acc, b)) -> acc -> s -> (acc, t) mapAccumROf :: Traversal s t a b -> (acc -> a -> (acc, b)) -> acc -> s -> (acc, t)
mapAccumROf :: LensLike (Backwards (State acc)) s t a b -> (acc -> a -> (acc, b)) -> acc -> s -> (acc, t)
mapEq :: forall k1 k2 (s :: k1) (t :: k2) (a :: k1) (b :: k2) f . AnEquality s t a b -> f s -> f alens Control.Lens.Combinators We can use Equality to do substitution into anything.
mapMOf :: LensLike (WrappedMonad m) s t a b -> (a -> m b) -> s -> m tlens Control.Lens.Combinators Map each element of a structure targeted by a Lens to a monadic action, evaluate these actions from left to right, and collect the results.
>>> mapMOf both (\x -> [x, x + 1]) (1,3) [(1,3),(1,4),(2,3),(2,4)]
mapM ≡ mapMOf traverse imapMOf l ≡ forM l . Indexed
mapMOf :: Monad m => Iso s t a b -> (a -> m b) -> s -> m t mapMOf :: Monad m => Lens s t a b -> (a -> m b) -> s -> m t mapMOf :: Monad m => Traversal s t a b -> (a -> m b) -> s -> m t
mapMOf_ :: Monad m => Getting (Sequenced r m) s a -> (a -> m r) -> s -> m ()lens Control.Lens.Combinators Map each target of a Fold on a structure to a monadic action, evaluate these actions from left to right, and ignore the results.
>>> mapMOf_ both putStrLn ("hello","world") hello worldmapM_ ≡ mapMOf_ folded
mapMOf_ :: Monad m => Getter s a -> (a -> m r) -> s -> m () mapMOf_ :: Monad m => Fold s a -> (a -> m r) -> s -> m () mapMOf_ :: Monad m => Lens' s a -> (a -> m r) -> s -> m () mapMOf_ :: Monad m => Iso' s a -> (a -> m r) -> s -> m () mapMOf_ :: Monad m => Traversal' s a -> (a -> m r) -> s -> m () mapMOf_ :: Monad m => Prism' s a -> (a -> m r) -> s -> m ()
mapOf :: ASetter s t a b -> (a -> b) -> s -> tlens Control.Lens.Combinators Deprecated: Use over
mapped :: forall (f :: Type -> Type) a b . Functor f => Setter (f a) (f b) a blens Control.Lens.Combinators This Setter can be used to map over all of the values in a Functor.
fmap ≡ over mapped fmapDefault ≡ over traverse (<$) ≡ set mapped
>>> over mapped f [a,b,c] [f a,f b,f c]
>>> over mapped (+1) [1,2,3] [2,3,4]
>>> set mapped x [a,b,c] [x,x,x]
>>> [[a,b],[c]] & mapped.mapped +~ x [[a + x,b + x],[c + x]]
>>> over (mapped._2) length [("hello","world"),("leaders","!!!")] [("hello",5),("leaders",3)]mapped :: Functor f => Setter (f a) (f b) a b
If you want an IndexPreservingSetter use setting fmap.-
lens Control.Lens.Combinators mappingNamer :: (String -> [String]) -> FieldNamerlens Control.Lens.Combinators Create a FieldNamer from a mapping function. If the function returns [], it creates no lens for the field.
mapEq :: forall k1 k2 (s :: k1) (t :: k2) (a :: k1) (b :: k2) f . AnEquality s t a b -> f s -> f alens Control.Lens.Equality We can use Equality to do substitution into anything.
mapMOf_ :: Monad m => Getting (Sequenced r m) s a -> (a -> m r) -> s -> m ()lens Control.Lens.Fold Map each target of a Fold on a structure to a monadic action, evaluate these actions from left to right, and ignore the results.
>>> mapMOf_ both putStrLn ("hello","world") hello worldmapM_ ≡ mapMOf_ folded
mapMOf_ :: Monad m => Getter s a -> (a -> m r) -> s -> m () mapMOf_ :: Monad m => Fold s a -> (a -> m r) -> s -> m () mapMOf_ :: Monad m => Lens' s a -> (a -> m r) -> s -> m () mapMOf_ :: Monad m => Iso' s a -> (a -> m r) -> s -> m () mapMOf_ :: Monad m => Traversal' s a -> (a -> m r) -> s -> m () mapMOf_ :: Monad m => Prism' s a -> (a -> m r) -> s -> m ()