Copyright	(C) 2012-16 Edward Kmett
License	BSD-style (see the file LICENSE)
Maintainer	Edward Kmett <ekmett@gmail.com>
Stability	experimental
Portability	non-portable
Safe Haskell	Trustworthy
Language	Haskell98

Control.Lens.At

Contents

At
Ixed
Contains

Description

Synopsis

class Ixed m => At m where
sans :: At m => Index m -> m -> m
iat :: At m => Index m -> IndexedLens' (Index m) m (Maybe (IxValue m))
type family Index (s :: *) :: *
type family IxValue (m :: *) :: *
class Ixed m where
ixAt :: At m => Index m -> Traversal' m (IxValue m)
iix :: Ixed m => Index m -> IndexedTraversal' (Index m) m (IxValue m)
class Contains m where
icontains :: Contains m => Index m -> IndexedLens' (Index m) m Bool

At

class Ixed m => At m where Source #

At provides a Lens that can be used to read, write or delete the value associated with a key in a Map-like container on an ad hoc basis.

An instance of At should satisfy:

ix k ≡ at k . traverse

Minimal complete definition

at

Methods

at :: Index m -> Lens' m (Maybe (IxValue m)) Source #

>>> Map.fromList [(1,"world")] ^.at 1
Just "world"

>>> at 1 ?~ "hello" $ Map.empty
fromList [(1,"hello")]

Note: Map-like containers form a reasonable instance, but not Array-like ones, where you cannot satisfy the Lens laws.

Instances

At IntSet Source #
Instance details Methods at :: Index IntSet -> Lens' IntSet (Maybe (IxValue IntSet)) Source #
At (Maybe a) Source #
Instance details Methods at :: Index (Maybe a) -> Lens' (Maybe a) (Maybe (IxValue (Maybe a))) Source #
At (IntMap a) Source #
Instance details Methods at :: Index (IntMap a) -> Lens' (IntMap a) (Maybe (IxValue (IntMap a))) Source #
Ord k => At (Set k) Source #
Instance details Methods at :: Index (Set k) -> Lens' (Set k) (Maybe (IxValue (Set k))) Source #
(Eq k, Hashable k) => At (HashSet k) Source #
Instance details Methods at :: Index (HashSet k) -> Lens' (HashSet k) (Maybe (IxValue (HashSet k))) Source #
Ord k => At (Map k a) Source #
Instance details Methods at :: Index (Map k a) -> Lens' (Map k a) (Maybe (IxValue (Map k a))) Source #
(Eq k, Hashable k) => At (HashMap k a) Source #
Instance details Methods at :: Index (HashMap k a) -> Lens' (HashMap k a) (Maybe (IxValue (HashMap k a))) Source #

sans :: At m => Index m -> m -> m Source #

Delete the value associated with a key in a Map-like container

sans k = at k .~ Nothing

iat :: At m => Index m -> IndexedLens' (Index m) m (Maybe (IxValue m)) Source #

An indexed version of at.

>>> Map.fromList [(1,"world")] ^@. iat 1
(1,Just "world")

>>> iat 1 %@~ (\i x -> if odd i then Just "hello" else Nothing) $ Map.empty
fromList [(1,"hello")]

>>> iat 2 %@~ (\i x -> if odd i then Just "hello" else Nothing) $ Map.empty
fromList []

Ixed

type family Index (s :: *) :: * Source #

Instances

type Index ByteString Source #
Instance details type Index ByteString = Int64
type Index ByteString Source #
Instance details type Index ByteString = Int
type Index IntSet Source #
Instance details type Index IntSet = Int
type Index Text Source #
Instance details type Index Text = Int64
type Index Text Source #
Instance details type Index Text = Int
type Index [a] Source #
Instance details type Index [a] = Int
type Index (Maybe a) Source #
Instance details type Index (Maybe a) = ()
type Index (Complex a) Source #
Instance details type Index (Complex a) = Int
type Index (NonEmpty a) Source #
Instance details type Index (NonEmpty a) = Int
type Index (Identity a) Source #
Instance details type Index (Identity a) = ()
type Index (IntMap a) Source #
Instance details type Index (IntMap a) = Int
type Index (Tree a) Source #
Instance details type Index (Tree a) = [Int]
type Index (Seq a) Source #
Instance details type Index (Seq a) = Int
type Index (Set a) Source #
Instance details type Index (Set a) = a
type Index (HashSet a) Source #
Instance details type Index (HashSet a) = a
type Index (Vector a) Source #
Instance details type Index (Vector a) = Int
type Index (Vector a) Source #
Instance details type Index (Vector a) = Int
type Index (Vector a) Source #
Instance details type Index (Vector a) = Int
type Index (Vector a) Source #
Instance details type Index (Vector a) = Int
type Index (e -> a) Source #
Instance details type Index (e -> a) = e
type Index (a, b) Source #
Instance details type Index (a, b) = Int
type Index (UArray i e) Source #
Instance details type Index (UArray i e) = i
type Index (Array i e) Source #
Instance details type Index (Array i e) = i
type Index (Map k a) Source #
Instance details type Index (Map k a) = k
type Index (HashMap k a) Source #
Instance details type Index (HashMap k a) = k
type Index (a, b, c) Source #
Instance details type Index (a, b, c) = Int
type Index (a, b, c, d) Source #
Instance details type Index (a, b, c, d) = Int
type Index (a, b, c, d, e) Source #
Instance details type Index (a, b, c, d, e) = Int
type Index (a, b, c, d, e, f) Source #
Instance details type Index (a, b, c, d, e, f) = Int
type Index (a, b, c, d, e, f, g) Source #
Instance details type Index (a, b, c, d, e, f, g) = Int
type Index (a, b, c, d, e, f, g, h) Source #
Instance details type Index (a, b, c, d, e, f, g, h) = Int
type Index (a, b, c, d, e, f, g, h, i) Source #
Instance details type Index (a, b, c, d, e, f, g, h, i) = Int

type family IxValue (m :: *) :: * Source #

This provides a common notion of a value at an index that is shared by both Ixed and At.

Instances

type IxValue ByteString Source #
Instance details type IxValue ByteString = Word8
type IxValue ByteString Source #
Instance details type IxValue ByteString = Word8
type IxValue IntSet Source #
Instance details type IxValue IntSet = ()
type IxValue Text Source #
Instance details type IxValue Text = Char
type IxValue Text Source #
Instance details type IxValue Text = Char
type IxValue [a] Source #
Instance details type IxValue [a] = a
type IxValue (Maybe a) Source #
Instance details type IxValue (Maybe a) = a
type IxValue (NonEmpty a) Source #
Instance details type IxValue (NonEmpty a) = a
type IxValue (Identity a) Source #
Instance details type IxValue (Identity a) = a
type IxValue (IntMap a) Source #
Instance details type IxValue (IntMap a) = a
type IxValue (Tree a) Source #
Instance details type IxValue (Tree a) = a
type IxValue (Seq a) Source #
Instance details type IxValue (Seq a) = a
type IxValue (Set k) Source #
Instance details type IxValue (Set k) = ()
type IxValue (HashSet k) Source #
Instance details type IxValue (HashSet k) = ()
type IxValue (Vector a) Source #
Instance details type IxValue (Vector a) = a
type IxValue (Vector a) Source #
Instance details type IxValue (Vector a) = a
type IxValue (Vector a) Source #
Instance details type IxValue (Vector a) = a
type IxValue (Vector a) Source #
Instance details type IxValue (Vector a) = a
type IxValue (e -> a) Source #
Instance details type IxValue (e -> a) = a
type IxValue (a, a2) Source #
Instance details type IxValue (a, a2) = a
type IxValue (UArray i e) Source #
Instance details type IxValue (UArray i e) = e
type IxValue (Array i e) Source #
Instance details type IxValue (Array i e) = e
type IxValue (Map k a) Source #
Instance details type IxValue (Map k a) = a
type IxValue (HashMap k a) Source #
Instance details type IxValue (HashMap k a) = a
type IxValue (a, a2, a3) Source #
Instance details type IxValue (a, a2, a3) = a
type IxValue (a, a2, a3, a4) Source #
Instance details type IxValue (a, a2, a3, a4) = a
type IxValue (a, a2, a3, a4, a5) Source #
Instance details type IxValue (a, a2, a3, a4, a5) = a
type IxValue (a, a2, a3, a4, a5, a6) Source #
Instance details type IxValue (a, a2, a3, a4, a5, a6) = a
type IxValue (a, a2, a3, a4, a5, a6, a7) Source #
Instance details type IxValue (a, a2, a3, a4, a5, a6, a7) = a
type IxValue (a, a2, a3, a4, a5, a6, a7, a8) Source #
Instance details type IxValue (a, a2, a3, a4, a5, a6, a7, a8) = a
type IxValue (a, a2, a3, a4, a5, a6, a7, a8, a9) Source #
Instance details type IxValue (a, a2, a3, a4, a5, a6, a7, a8, a9) = a

class Ixed m where Source #

Provides a simple Traversal lets you traverse the value at a given key in a Map or element at an ordinal position in a list or Seq.

Methods

ix :: Index m -> Traversal' m (IxValue m) Source #

NB: Setting the value of this Traversal will only set the value in at if it is already present.

If you want to be able to insert missing values, you want at.

>>> Seq.fromList [a,b,c,d] & ix 2 %~ f
fromList [a,b,f c,d]

>>> Seq.fromList [a,b,c,d] & ix 2 .~ e
fromList [a,b,e,d]

>>> Seq.fromList [a,b,c,d] ^? ix 2
Just c

>>> Seq.fromList [] ^? ix 2
Nothing

ix :: (Applicative f, At m) => Index m -> LensLike' f m (IxValue m) Source #

NB: Setting the value of this Traversal will only set the value in at if it is already present.

If you want to be able to insert missing values, you want at.

>>> Seq.fromList [a,b,c,d] & ix 2 %~ f
fromList [a,b,f c,d]

>>> Seq.fromList [a,b,c,d] & ix 2 .~ e
fromList [a,b,e,d]

>>> Seq.fromList [a,b,c,d] ^? ix 2
Just c

>>> Seq.fromList [] ^? ix 2
Nothing

Instances

Ixed ByteString Source #
Instance details Methods ix :: Index ByteString -> Traversal' ByteString (IxValue ByteString) Source #
Ixed ByteString Source #
Instance details Methods ix :: Index ByteString -> Traversal' ByteString (IxValue ByteString) Source #
Ixed IntSet Source #
Instance details Methods ix :: Index IntSet -> Traversal' IntSet (IxValue IntSet) Source #
Ixed Text Source #
Instance details Methods ix :: Index Text -> Traversal' Text (IxValue Text) Source #
Ixed Text Source #
Instance details Methods ix :: Index Text -> Traversal' Text (IxValue Text) Source #
Ixed [a] Source #
Instance details Methods ix :: Index [a] -> Traversal' [a] (IxValue [a]) Source #
Ixed (Maybe a) Source #
Instance details Methods ix :: Index (Maybe a) -> Traversal' (Maybe a) (IxValue (Maybe a)) Source #
Ixed (NonEmpty a) Source #
Instance details Methods ix :: Index (NonEmpty a) -> Traversal' (NonEmpty a) (IxValue (NonEmpty a)) Source #
Ixed (Identity a) Source #
Instance details Methods ix :: Index (Identity a) -> Traversal' (Identity a) (IxValue (Identity a)) Source #
Ixed (IntMap a) Source #
Instance details Methods ix :: Index (IntMap a) -> Traversal' (IntMap a) (IxValue (IntMap a)) Source #
Ixed (Tree a) Source #
Instance details Methods ix :: Index (Tree a) -> Traversal' (Tree a) (IxValue (Tree a)) Source #
Ixed (Seq a) Source #
Instance details Methods ix :: Index (Seq a) -> Traversal' (Seq a) (IxValue (Seq a)) Source #
Ord k => Ixed (Set k) Source #
Instance details Methods ix :: Index (Set k) -> Traversal' (Set k) (IxValue (Set k)) Source #
(Eq k, Hashable k) => Ixed (HashSet k) Source #
Instance details Methods ix :: Index (HashSet k) -> Traversal' (HashSet k) (IxValue (HashSet k)) Source #
Unbox a => Ixed (Vector a) Source #
Instance details Methods ix :: Index (Vector a) -> Traversal' (Vector a) (IxValue (Vector a)) Source #
Storable a => Ixed (Vector a) Source #
Instance details Methods ix :: Index (Vector a) -> Traversal' (Vector a) (IxValue (Vector a)) Source #
Prim a => Ixed (Vector a) Source #
Instance details Methods ix :: Index (Vector a) -> Traversal' (Vector a) (IxValue (Vector a)) Source #
Ixed (Vector a) Source #
Instance details Methods ix :: Index (Vector a) -> Traversal' (Vector a) (IxValue (Vector a)) Source #
Eq e => Ixed (e -> a) Source #
Instance details Methods ix :: Index (e -> a) -> Traversal' (e -> a) (IxValue (e -> a)) Source #
(~) * a a2 => Ixed (a, a2) Source #
Instance details Methods ix :: Index (a, a2) -> Traversal' (a, a2) (IxValue (a, a2)) Source #
(IArray UArray e, Ix i) => Ixed (UArray i e) Source #	arr `!` i ≡ arr `^.` `ix` i arr `//` [(i,e)] ≡ `ix` i `.~` e `$` arr
Instance details Methods ix :: Index (UArray i e) -> Traversal' (UArray i e) (IxValue (UArray i e)) Source #
Ix i => Ixed (Array i e) Source #	arr `!` i ≡ arr `^.` `ix` i arr `//` [(i,e)] ≡ `ix` i `.~` e `$` arr
Instance details Methods ix :: Index (Array i e) -> Traversal' (Array i e) (IxValue (Array i e)) Source #
Ord k => Ixed (Map k a) Source #
Instance details Methods ix :: Index (Map k a) -> Traversal' (Map k a) (IxValue (Map k a)) Source #
(Eq k, Hashable k) => Ixed (HashMap k a) Source #
Instance details Methods ix :: Index (HashMap k a) -> Traversal' (HashMap k a) (IxValue (HashMap k a)) Source #
((~) * a a2, (~) * a a3) => Ixed (a, a2, a3) Source #
Instance details Methods ix :: Index (a, a2, a3) -> Traversal' (a, a2, a3) (IxValue (a, a2, a3)) Source #
((~) * a a2, (~) * a a3, (~) * a a4) => Ixed (a, a2, a3, a4) Source #
Instance details Methods ix :: Index (a, a2, a3, a4) -> Traversal' (a, a2, a3, a4) (IxValue (a, a2, a3, a4)) Source #
((~) * a a2, (~) * a a3, (~) * a a4, (~) * a a5) => Ixed (a, a2, a3, a4, a5) Source #
Instance details Methods ix :: Index (a, a2, a3, a4, a5) -> Traversal' (a, a2, a3, a4, a5) (IxValue (a, a2, a3, a4, a5)) Source #
((~) * a a2, (~) * a a3, (~) * a a4, (~) * a a5, (~) * a a6) => Ixed (a, a2, a3, a4, a5, a6) Source #
Instance details Methods ix :: Index (a, a2, a3, a4, a5, a6) -> Traversal' (a, a2, a3, a4, a5, a6) (IxValue (a, a2, a3, a4, a5, a6)) Source #
((~) * a a2, (~) * a a3, (~) * a a4, (~) * a a5, (~) * a a6, (~) * a a7) => Ixed (a, a2, a3, a4, a5, a6, a7) Source #
Instance details Methods ix :: Index (a, a2, a3, a4, a5, a6, a7) -> Traversal' (a, a2, a3, a4, a5, a6, a7) (IxValue (a, a2, a3, a4, a5, a6, a7)) Source #
((~) * a a2, (~) * a a3, (~) * a a4, (~) * a a5, (~) * a a6, (~) * a a7, (~) * a a8) => Ixed (a, a2, a3, a4, a5, a6, a7, a8) Source #
Instance details Methods ix :: Index (a, a2, a3, a4, a5, a6, a7, a8) -> Traversal' (a, a2, a3, a4, a5, a6, a7, a8) (IxValue (a, a2, a3, a4, a5, a6, a7, a8)) Source #
((~) * a a2, (~) * a a3, (~) * a a4, (~) * a a5, (~) * a a6, (~) * a a7, (~) * a a8, (~) * a a9) => Ixed (a, a2, a3, a4, a5, a6, a7, a8, a9) Source #
Instance details Methods ix :: Index (a, a2, a3, a4, a5, a6, a7, a8, a9) -> Traversal' (a, a2, a3, a4, a5, a6, a7, a8, a9) (IxValue (a, a2, a3, a4, a5, a6, a7, a8, a9)) Source #

ixAt :: At m => Index m -> Traversal' m (IxValue m) Source #

A definition of ix for types with an At instance. This is the default if you don't specify a definition for ix.

iix :: Ixed m => Index m -> IndexedTraversal' (Index m) m (IxValue m) Source #

An indexed version of ix.

>>> Seq.fromList [a,b,c,d] & iix 2 %@~ f'
fromList [a,b,f' 2 c,d]

>>> Seq.fromList [a,b,c,d] & iix 2 .@~ h
fromList [a,b,h 2,d]

>>> Seq.fromList [a,b,c,d] ^@? iix 2
Just (2,c)

>>> Seq.fromList [] ^@? iix 2
Nothing

Contains

class Contains m where Source #

This class provides a simple Lens that lets you view (and modify) information about whether or not a container contains a given Index.

Minimal complete definition

contains

Methods

contains :: Index m -> Lens' m Bool Source #

>>> IntSet.fromList [1,2,3,4] ^. contains 3
True

>>> IntSet.fromList [1,2,3,4] ^. contains 5
False

>>> IntSet.fromList [1,2,3,4] & contains 3 .~ False
fromList [1,2,4]

Instances

Contains IntSet Source #
Instance details Methods contains :: Index IntSet -> Lens' IntSet Bool Source #
Ord a => Contains (Set a) Source #
Instance details Methods contains :: Index (Set a) -> Lens' (Set a) Bool Source #
(Eq a, Hashable a) => Contains (HashSet a) Source #
Instance details Methods contains :: Index (HashSet a) -> Lens' (HashSet a) Bool Source #

icontains :: Contains m => Index m -> IndexedLens' (Index m) m Bool Source #

An indexed version of contains.

>>> IntSet.fromList [1,2,3,4] ^@. icontains 3
(3,True)

>>> IntSet.fromList [1,2,3,4] ^@. icontains 5
(5,False)

>>> IntSet.fromList [1,2,3,4] & icontains 3 %@~ \i x -> if odd i then not x else x
fromList [1,2,4]

>>> IntSet.fromList [1,2,3,4] & icontains 3 %@~ \i x -> if even i then not x else x
fromList [1,2,3,4]