.~ package:lens

Replace the target of a Lens or all of the targets of a Setter or Traversal with a constant value. This is an infix version of set, provided for consistency with (.=).

f <$ a ≡ mapped .~ f $ a

>>> (a,b,c,d) & _4 .~ e
(a,b,c,e)

>>> (42,"world") & _1 .~ "hello"
("hello","world")

>>> (a,b) & both .~ c
(c,c)

(.~) :: Setter s t a b    -> b -> s -> t
(.~) :: Iso s t a b       -> b -> s -> t
(.~) :: Lens s t a b      -> b -> s -> t
(.~) :: Traversal s t a b -> b -> s -> t

Replace the target of a Lens, but return the old value. When you do not need the old value, (.~) is more flexible.

(<<.~) ::             Lens s t a b      -> b -> s -> (a, t)
(<<.~) ::             Iso s t a b       -> b -> s -> (a, t)
(<<.~) :: Monoid a => Traversal s t a b -> b -> s -> (a, t)

Set with pass-through. This is mostly present for consistency, but may be useful for chaining assignments. If you do not need a copy of the intermediate result, then using l .~ t directly is a good idea.

>>> (a,b) & _1 <.~ c
(c,(c,b))

>>> ("good","morning","vietnam") & _3 <.~ "world"
("world",("good","morning","world"))

>>> (42,Map.fromList [("goodnight","gracie")]) & _2.at "hello" <.~ Just "world"
(Just "world",(42,fromList [("goodnight","gracie"),("hello","world")]))

(<.~) :: Setter s t a b    -> b -> s -> (b, t)
(<.~) :: Iso s t a b       -> b -> s -> (b, t)
(<.~) :: Lens s t a b      -> b -> s -> (b, t)
(<.~) :: Traversal s t a b -> b -> s -> (b, t)

Bitwise .&. the target(s) of a Lens or Setter.

>>> _2 .&.~ 7 $ ("hello",254)
("hello",6)

(.&.~) :: Bits a             => Setter s t a a    -> a -> s -> t
(.&.~) :: Bits a             => Iso s t a a       -> a -> s -> t
(.&.~) :: Bits a             => Lens s t a a      -> a -> s -> t
(.&.~) :: (Monoid a, Bits a) => Traversal s t a a -> a -> s -> t

Bitwise .|. the target(s) of a Lens or Setter.

>>> _2 .|.~ 6 $ ("hello",3)
("hello",7)

(.|.~) :: Bits a             => Setter s t a a    -> a -> s -> t
(.|.~) :: Bits a             => Iso s t a a       -> a -> s -> t
(.|.~) :: Bits a             => Lens s t a a      -> a -> s -> t
(.|.~) :: (Monoid a, Bits a) => Traversal s t a a -> a -> s -> t

Bitwise .&. the target(s) of a Lens or Traversal, returning the result (or a monoidal summary of all of the results).

>>> _2 <.&.~ 7 $ ("hello",254)
(6,("hello",6))

(<.&.~) :: Bits a             => Iso       s t a a -> a -> s -> (a, t)
(<.&.~) :: Bits a             => Lens      s t a a -> a -> s -> (a, t)
(<.&.~) :: (Bits a, Monoid a) => Traversal s t a a -> a -> s -> (a, t)

Bitwise .|. the target(s) of a Lens (or Traversal), returning the result (or a monoidal summary of all of the results).

>>> _2 <.|.~ 6 $ ("hello",3)
(7,("hello",7))

(<.|.~) :: Bits a             => Iso s t a a       -> a -> s -> (a, t)
(<.|.~) :: Bits a             => Lens s t a a      -> a -> s -> (a, t)
(<.|.~) :: (Bits a, Monoid a) => Traversal s t a a -> a -> s -> (a, t)

Bitwise .&. the target(s) of a Lens or Traversal, and return the original value, or a monoidal summary of the original values. When you do not need the old value, (.&.~) is more flexible.

>>> _2 <<.&.~ 7 $ ("hello", 254)
(254,("hello",6))

(<<.&.~) ::  Bits a            => Iso s t a a       -> a -> s -> (a, t)
(<<.&.~) ::  Bits a            => Lens s t a a      -> a -> s -> (a, t)
(<<.&.~) :: (Bits a, Monoid a) => Traversal s t a a -> a -> s -> (a, t)

Bitwise .|. the target(s) of a Lens or Traversal, and return the original value, or a monoidal summary of the original values. When you do not need the old value, (.|.~) is more flexible.

>>> _2 <<.|.~ 6 $ ("hello", 3)
(3,("hello",7))

(<<.|.~) ::  Bits a            => Iso s t a a       -> a -> s -> (a, t)
(<<.|.~) ::  Bits a            => Lens s t a a      -> a -> s -> (a, t)
(<<.|.~) :: (Bits a, Monoid a) => Traversal s t a a -> a -> s -> (a, t)