Safe Haskell	Safe
Language	Haskell98

Lens.Family.Clone

Contents

Types
Re-exports

Description

This module is provided for Haskell 98 compatibility. If you are able to use Rank2Types, I advise you to instead use the rank 2 aliases

Lens, Lens'
Traversal, Traversal'
Setter, Setter'
Fold, Fold'
Getter, Getter'

from the lens-family package instead.

cloneLens allows one to circumvent the need for rank 2 types by allowing one to take a universal monomorphic lens instance and rederive a polymorphic instance. When you require a lens family parameter you use the type ALens a a' b b' (or ALens' a b). Then, inside a where clause, you use cloneLens to create a Lens type.

For example.

example :: ALens a a' b b' -> Example
example l = ... x^.cl ... cl .~ y ...
 where
  cl x = cloneLens l x

Note: It is important to eta-expand the definition of cl to avoid the dreaded monomorphism restriction.

cloneTraversal, cloneGetter, cloneSetter, and cloneFold provides similar functionality for traversals, getters, setters, and folds respectively.

Note: Cloning is only need if you use a functional reference multiple times with different instances.

Synopsis

Documentation

cloneLens :: Functor f => ALens a a' b b' -> LensLike f a a' b b' #

Converts a universal lens instance back into a polymorphic lens.

cloneTraversal :: Applicative f => ATraversal a a' b b' -> LensLike f a a' b b' #

Converts a universal traversal instance back into a polymorphic traversal.

cloneSetter :: Identical f => ASetter a a' b b' -> LensLike f a a' b b' #

Converts a universal setter instance back into a polymorphic setter.

cloneGetter :: Phantom f => AGetter a a' b b' -> LensLike f a a' b b' #

Converts a universal getter instance back into a polymorphic getter.

cloneFold :: (Phantom f, Applicative f) => AFold a a' b b' -> LensLike f a a' b b' #

Converts a universal fold instance back into a polymorphic fold.

Types

type ALens a a' b b' = LensLike (IStore b b') a a' b b' #

ALens a a' b b' is a universal Lens a a' b b' instance

type ALens' a b = LensLike' (IStore b b) a b #

ALens' a b is a universal Lens' a b instance

type ATraversal a a' b b' = LensLike (IKleeneStore b b') a a' b b' #

ATraversal a a' b b' is a universal Traversal a a' b b' instance

type ATraversal' a b = LensLike' (IKleeneStore b b) a b #

ATraversal' a b is a universal Traversal' a b instance

type AGetter a a' b b' = FoldLike b a a' b b' #

AGetter a a' b b' is a universal Fold a a' b b' instance

type AGetter' a b = FoldLike' b a b #

AGetter' a b is a universal Fold' a b instance

type AFold a a' b b' = FoldLike [b] a a' b b' #

AFold a a' b b' is a universal Fold' a a' b b' instance

type AFold' a b = FoldLike' [b] a b #

AFold' a b is a universal Fold' a b instance

data IStore b b' a #

Instances

Functor (IStore b b') #
Methods fmap :: (a -> b) -> IStore b b' a -> IStore b b' b # (<$) :: a -> IStore b b' b -> IStore b b' a #

data IKleeneStore b b' a #

Instances

Functor (IKleeneStore b b') #
Methods fmap :: (a -> b) -> IKleeneStore b b' a -> IKleeneStore b b' b # (<$) :: a -> IKleeneStore b b' b -> IKleeneStore b b' a #
Applicative (IKleeneStore b b') #
Methods pure :: a -> IKleeneStore b b' a # (<>) :: IKleeneStore b b' (a -> b) -> IKleeneStore b b' a -> IKleeneStore b b' b # liftA2 :: (a -> b -> c) -> IKleeneStore b b' a -> IKleeneStore b b' b -> IKleeneStore b b' c # (>) :: IKleeneStore b b' a -> IKleeneStore b b' b -> IKleeneStore b b' b # (<*) :: IKleeneStore b b' a -> IKleeneStore b b' b -> IKleeneStore b b' a #

Re-exports

type LensLike f a a' b b' = (b -> f b') -> a -> f a' #

type LensLike' f a b = (b -> f b) -> a -> f a #

type FoldLike r a a' b b' = LensLike (Constant r) a a' b b' #

type FoldLike' r a b = LensLike' (Constant r) a b #

type ASetter a a' b b' = LensLike Identity a a' b b' #

class Functor f => Applicative (f :: * -> *) #

A functor with application, providing operations to

embed pure expressions (pure), and
sequence computations and combine their results (<*> and liftA2).

A minimal complete definition must include implementations of pure and of either <*> or liftA2. If it defines both, then they must behave the same as their default definitions:

(<*>) = liftA2 id liftA2 f x y = f <$> x <*> y

Further, any definition must satisfy the following:

identity

pure id <*> v = v

composition

pure (.) <*> u <*> v <*> w = u <*> (v <*> w)

homomorphism

pure f <*> pure x = pure (f x)

interchange

u <*> pure y = pure ($ y) <*> u

The other methods have the following default definitions, which may be overridden with equivalent specialized implementations:

```
u *> v = (id <$ u) <*> v
```
```
u <* v = liftA2 const u v
```

As a consequence of these laws, the Functor instance for f will satisfy

```
fmap f x = pure f <*> x
```

It may be useful to note that supposing

forall x y. p (q x y) = f x . g y

it follows from the above that

liftA2 p (liftA2 q u v) = liftA2 f u . liftA2 g v

If f is also a Monad, it should satisfy

```
pure = return
```
```
(<*>) = ap
```

(which implies that pure and <*> satisfy the applicative functor laws).

Minimal complete definition

pure, ((<*>) | liftA2)

Instances

Applicative []	Since: 2.1
Methods pure :: a -> [a] # (<>) :: [a -> b] -> [a] -> [b] # liftA2 :: (a -> b -> c) -> [a] -> [b] -> [c] # (>) :: [a] -> [b] -> [b] # (<*) :: [a] -> [b] -> [a] #
Applicative Maybe	Since: 2.1
Methods pure :: a -> Maybe a # (<>) :: Maybe (a -> b) -> Maybe a -> Maybe b # liftA2 :: (a -> b -> c) -> Maybe a -> Maybe b -> Maybe c # (>) :: Maybe a -> Maybe b -> Maybe b # (<*) :: Maybe a -> Maybe b -> Maybe a #
Applicative IO	Since: 2.1
Methods pure :: a -> IO a # (<>) :: IO (a -> b) -> IO a -> IO b # liftA2 :: (a -> b -> c) -> IO a -> IO b -> IO c # (>) :: IO a -> IO b -> IO b # (<*) :: IO a -> IO b -> IO a #
Applicative Par1	Since: 4.9.0.0
Methods pure :: a -> Par1 a # (<>) :: Par1 (a -> b) -> Par1 a -> Par1 b # liftA2 :: (a -> b -> c) -> Par1 a -> Par1 b -> Par1 c # (>) :: Par1 a -> Par1 b -> Par1 b # (<*) :: Par1 a -> Par1 b -> Par1 a #
Applicative ZipList	f '<$>' 'ZipList' xs1 '<>' ... '<>' 'ZipList' xsN `ZipList` (zipWithN f xs1 ... xsN) where `zipWithN` refers to the `zipWith` function of the appropriate arity (`zipWith`, `zipWith3`, `zipWith4`, ...). For example: (\a b c -> stimes c [a, b]) <$> ZipList "abcd" <> ZipList "567" <> ZipList [1..] = ZipList (zipWith3 (\a b c -> stimes c [a, b]) "abcd" "567" [1..]) = ZipList {getZipList = ["a5","b6b6","c7c7c7"]} Since: 2.1
Methods pure :: a -> ZipList a # (<>) :: ZipList (a -> b) -> ZipList a -> ZipList b # liftA2 :: (a -> b -> c) -> ZipList a -> ZipList b -> ZipList c # (>) :: ZipList a -> ZipList b -> ZipList b # (<*) :: ZipList a -> ZipList b -> ZipList a #
Applicative Identity	Since: 4.8.0.0
Methods pure :: a -> Identity a # (<>) :: Identity (a -> b) -> Identity a -> Identity b # liftA2 :: (a -> b -> c) -> Identity a -> Identity b -> Identity c # (>) :: Identity a -> Identity b -> Identity b # (<*) :: Identity a -> Identity b -> Identity a #
Applicative Dual	Since: 4.8.0.0
Methods pure :: a -> Dual a # (<>) :: Dual (a -> b) -> Dual a -> Dual b # liftA2 :: (a -> b -> c) -> Dual a -> Dual b -> Dual c # (>) :: Dual a -> Dual b -> Dual b # (<*) :: Dual a -> Dual b -> Dual a #
Applicative Sum	Since: 4.8.0.0
Methods pure :: a -> Sum a # (<>) :: Sum (a -> b) -> Sum a -> Sum b # liftA2 :: (a -> b -> c) -> Sum a -> Sum b -> Sum c # (>) :: Sum a -> Sum b -> Sum b # (<*) :: Sum a -> Sum b -> Sum a #
Applicative Product	Since: 4.8.0.0
Methods pure :: a -> Product a # (<>) :: Product (a -> b) -> Product a -> Product b # liftA2 :: (a -> b -> c) -> Product a -> Product b -> Product c # (>) :: Product a -> Product b -> Product b # (<*) :: Product a -> Product b -> Product a #
Applicative First
Methods pure :: a -> First a # (<>) :: First (a -> b) -> First a -> First b # liftA2 :: (a -> b -> c) -> First a -> First b -> First c # (>) :: First a -> First b -> First b # (<*) :: First a -> First b -> First a #
Applicative Last
Methods pure :: a -> Last a # (<>) :: Last (a -> b) -> Last a -> Last b # liftA2 :: (a -> b -> c) -> Last a -> Last b -> Last c # (>) :: Last a -> Last b -> Last b # (<*) :: Last a -> Last b -> Last a #
Applicative (Either e)	Since: 3.0
Methods pure :: a -> Either e a # (<>) :: Either e (a -> b) -> Either e a -> Either e b # liftA2 :: (a -> b -> c) -> Either e a -> Either e b -> Either e c # (>) :: Either e a -> Either e b -> Either e b # (<*) :: Either e a -> Either e b -> Either e a #
Applicative (U1 *)	Since: 4.9.0.0
Methods pure :: a -> U1 * a # (<>) :: U1 (a -> b) -> U1 * a -> U1 * b # liftA2 :: (a -> b -> c) -> U1 * a -> U1 * b -> U1 * c # (>) :: U1 a -> U1 * b -> U1 * b # (<) :: U1 a -> U1 * b -> U1 * a #
Monoid a => Applicative ((,) a)	For tuples, the `Monoid` constraint on `a` determines how the first values merge. For example, `String`s concatenate: ("hello ", (+15)) <> ("world!", 2002) ("hello world!",2017) Since: 2.1*
Methods pure :: a -> (a, a) # (<>) :: (a, a -> b) -> (a, a) -> (a, b) # liftA2 :: (a -> b -> c) -> (a, a) -> (a, b) -> (a, c) # (>) :: (a, a) -> (a, b) -> (a, b) # (<*) :: (a, a) -> (a, b) -> (a, a) #
Monad m => Applicative (WrappedMonad m)	Since: 2.1
Methods pure :: a -> WrappedMonad m a # (<>) :: WrappedMonad m (a -> b) -> WrappedMonad m a -> WrappedMonad m b # liftA2 :: (a -> b -> c) -> WrappedMonad m a -> WrappedMonad m b -> WrappedMonad m c # (>) :: WrappedMonad m a -> WrappedMonad m b -> WrappedMonad m b # (<*) :: WrappedMonad m a -> WrappedMonad m b -> WrappedMonad m a #
Arrow a => Applicative (ArrowMonad a)	Since: 4.6.0.0
Methods pure :: a -> ArrowMonad a a # (<>) :: ArrowMonad a (a -> b) -> ArrowMonad a a -> ArrowMonad a b # liftA2 :: (a -> b -> c) -> ArrowMonad a a -> ArrowMonad a b -> ArrowMonad a c # (>) :: ArrowMonad a a -> ArrowMonad a b -> ArrowMonad a b # (<*) :: ArrowMonad a a -> ArrowMonad a b -> ArrowMonad a a #
Applicative (Proxy *)	Since: 4.7.0.0
Methods pure :: a -> Proxy * a # (<>) :: Proxy (a -> b) -> Proxy * a -> Proxy * b # liftA2 :: (a -> b -> c) -> Proxy * a -> Proxy * b -> Proxy * c # (>) :: Proxy a -> Proxy * b -> Proxy * b # (<) :: Proxy a -> Proxy * b -> Proxy * a #
Applicative f => Applicative (Rec1 * f)	Since: 4.9.0.0
Methods pure :: a -> Rec1 * f a # (<>) :: Rec1 f (a -> b) -> Rec1 * f a -> Rec1 * f b # liftA2 :: (a -> b -> c) -> Rec1 * f a -> Rec1 * f b -> Rec1 * f c # (>) :: Rec1 f a -> Rec1 * f b -> Rec1 * f b # (<) :: Rec1 f a -> Rec1 * f b -> Rec1 * f a #
Arrow a => Applicative (WrappedArrow a b)	Since: 2.1
Methods pure :: a -> WrappedArrow a b a # (<>) :: WrappedArrow a b (a -> b) -> WrappedArrow a b a -> WrappedArrow a b b # liftA2 :: (a -> b -> c) -> WrappedArrow a b a -> WrappedArrow a b b -> WrappedArrow a b c # (>) :: WrappedArrow a b a -> WrappedArrow a b b -> WrappedArrow a b b # (<*) :: WrappedArrow a b a -> WrappedArrow a b b -> WrappedArrow a b a #
Monoid m => Applicative (Const * m)	Since: 2.0.1
Methods pure :: a -> Const * m a # (<>) :: Const m (a -> b) -> Const * m a -> Const * m b # liftA2 :: (a -> b -> c) -> Const * m a -> Const * m b -> Const * m c # (>) :: Const m a -> Const * m b -> Const * m b # (<) :: Const m a -> Const * m b -> Const * m a #
Applicative f => Applicative (Alt * f)
Methods pure :: a -> Alt * f a # (<>) :: Alt f (a -> b) -> Alt * f a -> Alt * f b # liftA2 :: (a -> b -> c) -> Alt * f a -> Alt * f b -> Alt * f c # (>) :: Alt f a -> Alt * f b -> Alt * f b # (<) :: Alt f a -> Alt * f b -> Alt * f a #
(Applicative f, Monad f) => Applicative (WhenMissing f x)	Equivalent to `ReaderT k (ReaderT x (MaybeT f))`.
Methods pure :: a -> WhenMissing f x a # (<>) :: WhenMissing f x (a -> b) -> WhenMissing f x a -> WhenMissing f x b # liftA2 :: (a -> b -> c) -> WhenMissing f x a -> WhenMissing f x b -> WhenMissing f x c # (>) :: WhenMissing f x a -> WhenMissing f x b -> WhenMissing f x b # (<*) :: WhenMissing f x a -> WhenMissing f x b -> WhenMissing f x a #
Monoid a => Applicative (Constant * a)
Methods pure :: a -> Constant * a a # (<>) :: Constant a (a -> b) -> Constant * a a -> Constant * a b # liftA2 :: (a -> b -> c) -> Constant * a a -> Constant * a b -> Constant * a c # (>) :: Constant a a -> Constant * a b -> Constant * a b # (<) :: Constant a a -> Constant * a b -> Constant * a a #
(Monoid w, Applicative m) => Applicative (WriterT w m)
Methods pure :: a -> WriterT w m a # (<>) :: WriterT w m (a -> b) -> WriterT w m a -> WriterT w m b # liftA2 :: (a -> b -> c) -> WriterT w m a -> WriterT w m b -> WriterT w m c # (>) :: WriterT w m a -> WriterT w m b -> WriterT w m b # (<*) :: WriterT w m a -> WriterT w m b -> WriterT w m a #
(Functor m, Monad m) => Applicative (StateT s m)
Methods pure :: a -> StateT s m a # (<>) :: StateT s m (a -> b) -> StateT s m a -> StateT s m b # liftA2 :: (a -> b -> c) -> StateT s m a -> StateT s m b -> StateT s m c # (>) :: StateT s m a -> StateT s m b -> StateT s m b # (<*) :: StateT s m a -> StateT s m b -> StateT s m a #
(Functor m, Monad m) => Applicative (StateT s m)
Methods pure :: a -> StateT s m a # (<>) :: StateT s m (a -> b) -> StateT s m a -> StateT s m b # liftA2 :: (a -> b -> c) -> StateT s m a -> StateT s m b -> StateT s m c # (>) :: StateT s m a -> StateT s m b -> StateT s m b # (<*) :: StateT s m a -> StateT s m b -> StateT s m a #
Applicative f => Applicative (Backwards * f)	Apply `f`-actions in the reverse order.
Methods pure :: a -> Backwards * f a # (<>) :: Backwards f (a -> b) -> Backwards * f a -> Backwards * f b # liftA2 :: (a -> b -> c) -> Backwards * f a -> Backwards * f b -> Backwards * f c # (>) :: Backwards f a -> Backwards * f b -> Backwards * f b # (<) :: Backwards f a -> Backwards * f b -> Backwards * f a #
(Monoid c, Monad m) => Applicative (Zooming m c) #
Methods pure :: a -> Zooming m c a # (<>) :: Zooming m c (a -> b) -> Zooming m c a -> Zooming m c b # liftA2 :: (a -> b -> c) -> Zooming m c a -> Zooming m c b -> Zooming m c c # (>) :: Zooming m c a -> Zooming m c b -> Zooming m c b # (<*) :: Zooming m c a -> Zooming m c b -> Zooming m c a #
Applicative (IKleeneStore b b') #
Methods pure :: a -> IKleeneStore b b' a # (<>) :: IKleeneStore b b' (a -> b) -> IKleeneStore b b' a -> IKleeneStore b b' b # liftA2 :: (a -> b -> c) -> IKleeneStore b b' a -> IKleeneStore b b' b -> IKleeneStore b b' c # (>) :: IKleeneStore b b' a -> IKleeneStore b b' b -> IKleeneStore b b' b # (<*) :: IKleeneStore b b' a -> IKleeneStore b b' b -> IKleeneStore b b' a #
Applicative ((->) LiftedRep LiftedRep a)	Since: 2.1
Methods pure :: a -> (LiftedRep -> LiftedRep) a a # (<>) :: (LiftedRep -> LiftedRep) a (a -> b) -> (LiftedRep -> LiftedRep) a a -> (LiftedRep -> LiftedRep) a b # liftA2 :: (a -> b -> c) -> (LiftedRep -> LiftedRep) a a -> (LiftedRep -> LiftedRep) a b -> (LiftedRep -> LiftedRep) a c # (>) :: (LiftedRep -> LiftedRep) a a -> (LiftedRep -> LiftedRep) a b -> (LiftedRep -> LiftedRep) a b # (<*) :: (LiftedRep -> LiftedRep) a a -> (LiftedRep -> LiftedRep) a b -> (LiftedRep -> LiftedRep) a a #
(Applicative f, Applicative g) => Applicative ((::) f g)	Since: 4.9.0.0
Methods pure :: a -> (* :: f) g a # (<>) :: (* :: f) g (a -> b) -> ( :: f) g a -> ( :: f) g b # liftA2 :: (a -> b -> c) -> ( :: f) g a -> ( :: f) g b -> ( :: f) g c # (>) :: (* :: f) g a -> ( :: f) g b -> ( :: f) g b # (<) :: (* :: f) g a -> ( :: f) g b -> ( :*: f) g a #
(Monad f, Applicative f) => Applicative (WhenMatched f x y)	Equivalent to `ReaderT Key (ReaderT x (ReaderT y (MaybeT f)))`
Methods pure :: a -> WhenMatched f x y a # (<>) :: WhenMatched f x y (a -> b) -> WhenMatched f x y a -> WhenMatched f x y b # liftA2 :: (a -> b -> c) -> WhenMatched f x y a -> WhenMatched f x y b -> WhenMatched f x y c # (>) :: WhenMatched f x y a -> WhenMatched f x y b -> WhenMatched f x y b # (<*) :: WhenMatched f x y a -> WhenMatched f x y b -> WhenMatched f x y a #
(Applicative f, Monad f) => Applicative (WhenMissing f k x)	Equivalent to `ReaderT k (ReaderT x (MaybeT f))` .
Methods pure :: a -> WhenMissing f k x a # (<>) :: WhenMissing f k x (a -> b) -> WhenMissing f k x a -> WhenMissing f k x b # liftA2 :: (a -> b -> c) -> WhenMissing f k x a -> WhenMissing f k x b -> WhenMissing f k x c # (>) :: WhenMissing f k x a -> WhenMissing f k x b -> WhenMissing f k x b # (<*) :: WhenMissing f k x a -> WhenMissing f k x b -> WhenMissing f k x a #
Applicative f => Applicative (M1 * i c f)	Since: 4.9.0.0
Methods pure :: a -> M1 * i c f a # (<>) :: M1 i c f (a -> b) -> M1 * i c f a -> M1 * i c f b # liftA2 :: (a -> b -> c) -> M1 * i c f a -> M1 * i c f b -> M1 * i c f c # (>) :: M1 i c f a -> M1 * i c f b -> M1 * i c f b # (<) :: M1 i c f a -> M1 * i c f b -> M1 * i c f a #
(Applicative f, Applicative g) => Applicative ((:.:) * * f g)	Since: 4.9.0.0
Methods pure :: a -> (* :.: ) f g a # (<>) :: (* :.: ) f g (a -> b) -> ( :.: ) f g a -> ( :.: ) f g b # liftA2 :: (a -> b -> c) -> ( :.: ) f g a -> ( :.: ) f g b -> ( :.: ) f g c # (>) :: (* :.: ) f g a -> ( :.: ) f g b -> ( :.: ) f g b # (<) :: (* :.: ) f g a -> ( :.: ) f g b -> ( :.: *) f g a #
(Applicative f, Applicative g) => Applicative (Compose * * f g)	Since: 4.9.0.0
Methods pure :: a -> Compose * * f g a # (<>) :: Compose * f g (a -> b) -> Compose * * f g a -> Compose * * f g b # liftA2 :: (a -> b -> c) -> Compose * * f g a -> Compose * * f g b -> Compose * * f g c # (>) :: Compose * f g a -> Compose * * f g b -> Compose * * f g b # (<) :: Compose * f g a -> Compose * * f g b -> Compose * * f g a #
(Monad f, Applicative f) => Applicative (WhenMatched f k x y)	Equivalent to `ReaderT k (ReaderT x (ReaderT y (MaybeT f)))`
Methods pure :: a -> WhenMatched f k x y a # (<>) :: WhenMatched f k x y (a -> b) -> WhenMatched f k x y a -> WhenMatched f k x y b # liftA2 :: (a -> b -> c) -> WhenMatched f k x y a -> WhenMatched f k x y b -> WhenMatched f k x y c # (>) :: WhenMatched f k x y a -> WhenMatched f k x y b -> WhenMatched f k x y b # (<*) :: WhenMatched f k x y a -> WhenMatched f k x y b -> WhenMatched f k x y a #

class Functor f => Phantom f #

Minimal complete definition

coerce

Instances

Phantom (Const * a) #
Methods coerce :: Const * a a -> Const * a b
Phantom (Constant * a) #
Methods coerce :: Constant * a a -> Constant * a b
Phantom f => Phantom (Backwards * f) #
Methods coerce :: Backwards * f a -> Backwards * f b
Phantom f => Phantom (AlongsideRight f a) #
Methods coerce :: AlongsideRight f a a -> AlongsideRight f a b
Phantom f => Phantom (AlongsideLeft f a) #
Methods coerce :: AlongsideLeft f a a -> AlongsideLeft f a b
(Phantom f, Functor g) => Phantom (Compose * * f g) #
Methods coerce :: Compose * * f g a -> Compose * * f g b

class Applicative f => Identical f #

Minimal complete definition

extract

Instances

Identical Identity #
Methods extract :: Identity a -> a
Identical f => Identical (Backwards * f) #
Methods extract :: Backwards * f a -> a
(Identical f, Identical g) => Identical (Compose * * f g) #
Methods extract :: Compose * * f g a -> a

Documentation

Types

Re-exports

ZipList (zipWithN f xs1 ... xsN)

`ZipList` (zipWithN f xs1 ... xsN)