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 | Haskell2010 |
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
- ix :: Index m -> Traversal' m (IxValue m)
- 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
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
iat :: At m => Index m -> IndexedLens' (Index m) m (Maybe (IxValue m)) #
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 :: *) :: * #
Instances
type Index ByteString # | |
Defined in Control.Lens.At | |
type Index ByteString # | |
Defined in Control.Lens.At | |
type Index IntSet # | |
Defined in Control.Lens.At | |
type Index Text # | |
Defined in Control.Lens.At | |
type Index Text # | |
Defined in Control.Lens.At | |
type Index [a] # | |
Defined in Control.Lens.At | |
type Index (Maybe a) # | |
Defined in Control.Lens.At | |
type Index (Complex a) # | |
Defined in Control.Lens.At | |
type Index (Identity a) # | |
Defined in Control.Lens.At | |
type Index (NonEmpty a) # | |
Defined in Control.Lens.At | |
type Index (IntMap a) # | |
Defined in Control.Lens.At | |
type Index (Tree a) # | |
Defined in Control.Lens.At | |
type Index (Seq a) # | |
Defined in Control.Lens.At | |
type Index (Set a) # | |
Defined in Control.Lens.At | |
type Index (HashSet a) # | |
Defined in Control.Lens.At | |
type Index (Vector a) # | |
Defined in Control.Lens.At | |
type Index (Vector a) # | |
Defined in Control.Lens.At | |
type Index (Vector a) # | |
Defined in Control.Lens.At | |
type Index (Vector a) # | |
Defined in Control.Lens.At | |
type Index (e -> a) # | |
Defined in Control.Lens.At type Index (e -> a) = e | |
type Index (a, b) # | |
Defined in Control.Lens.At | |
type Index (UArray i e) # | |
Defined in Control.Lens.At | |
type Index (Array i e) # | |
Defined in Control.Lens.At | |
type Index (Map k a) # | |
Defined in Control.Lens.At | |
type Index (HashMap k a) # | |
Defined in Control.Lens.At | |
type Index (a, b, c) # | |
Defined in Control.Lens.At | |
type Index (a, b, c, d) # | |
Defined in Control.Lens.At | |
type Index (a, b, c, d, e) # | |
Defined in Control.Lens.At | |
type Index (a, b, c, d, e, f) # | |
Defined in Control.Lens.At | |
type Index (a, b, c, d, e, f, g) # | |
Defined in Control.Lens.At | |
type Index (a, b, c, d, e, f, g, h) # | |
Defined in Control.Lens.At | |
type Index (a, b, c, d, e, f, g, h, i) # | |
Defined in Control.Lens.At |
type family IxValue (m :: *) :: * #
Instances
type IxValue ByteString # | |
Defined in Control.Lens.At | |
type IxValue ByteString # | |
Defined in Control.Lens.At | |
type IxValue IntSet # | |
Defined in Control.Lens.At | |
type IxValue Text # | |
Defined in Control.Lens.At | |
type IxValue Text # | |
Defined in Control.Lens.At | |
type IxValue [a] # | |
Defined in Control.Lens.At type IxValue [a] = a | |
type IxValue (Maybe a) # | |
Defined in Control.Lens.At | |
type IxValue (Identity a) # | |
Defined in Control.Lens.At | |
type IxValue (NonEmpty a) # | |
Defined in Control.Lens.At | |
type IxValue (IntMap a) # | |
Defined in Control.Lens.At | |
type IxValue (Tree a) # | |
Defined in Control.Lens.At | |
type IxValue (Seq a) # | |
Defined in Control.Lens.At | |
type IxValue (Set k) # | |
Defined in Control.Lens.At | |
type IxValue (HashSet k) # | |
Defined in Control.Lens.At | |
type IxValue (Vector a) # | |
Defined in Control.Lens.At | |
type IxValue (Vector a) # | |
Defined in Control.Lens.At | |
type IxValue (Vector a) # | |
Defined in Control.Lens.At | |
type IxValue (Vector a) # | |
Defined in Control.Lens.At | |
type IxValue (e -> a) # | |
Defined in Control.Lens.At type IxValue (e -> a) = a | |
type IxValue (a, a2) # |
|
Defined in Control.Lens.At type IxValue (a, a2) = a | |
type IxValue (UArray i e) # | |
Defined in Control.Lens.At | |
type IxValue (Array i e) # | |
Defined in Control.Lens.At | |
type IxValue (Map k a) # | |
Defined in Control.Lens.At | |
type IxValue (HashMap k a) # | |
Defined in Control.Lens.At | |
type IxValue (a, a2, a3) # |
|
Defined in Control.Lens.At type IxValue (a, a2, a3) = a | |
type IxValue (a, a2, a3, a4) # |
|
Defined in Control.Lens.At type IxValue (a, a2, a3, a4) = a | |
type IxValue (a, a2, a3, a4, a5) # |
|
Defined in Control.Lens.At type IxValue (a, a2, a3, a4, a5) = a | |
type IxValue (a, a2, a3, a4, a5, a6) # |
|
Defined in Control.Lens.At type IxValue (a, a2, a3, a4, a5, a6) = a | |
type IxValue (a, a2, a3, a4, a5, a6, a7) # |
|
Defined in Control.Lens.At type IxValue (a, a2, a3, a4, a5, a6, a7) = a | |
type IxValue (a, a2, a3, a4, a5, a6, a7, a8) # |
|
Defined in Control.Lens.At type IxValue (a, a2, a3, a4, a5, a6, a7, a8) = a | |
type IxValue (a, a2, a3, a4, a5, a6, a7, a8, a9) # |
|
Defined in Control.Lens.At type IxValue (a, a2, a3, a4, a5, a6, a7, a8, a9) = a |
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
.
Nothing
ix :: Index m -> Traversal' m (IxValue m) #
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 # | |
Defined in Control.Lens.At ix :: Index ByteString -> Traversal' ByteString (IxValue ByteString) # | |
Ixed ByteString # | |
Defined in Control.Lens.At ix :: Index ByteString -> Traversal' ByteString (IxValue ByteString) # | |
Ixed IntSet # | |
Defined in Control.Lens.At | |
Ixed Text # | |
Defined in Control.Lens.At | |
Ixed Text # | |
Defined in Control.Lens.At | |
Ixed [a] # | |
Defined in Control.Lens.At ix :: Index [a] -> Traversal' [a] (IxValue [a]) # | |
Ixed (Maybe a) # | |
Defined in Control.Lens.At | |
Ixed (Identity a) # | |
Defined in Control.Lens.At | |
Ixed (NonEmpty a) # | |
Defined in Control.Lens.At | |
Ixed (IntMap a) # | |
Defined in Control.Lens.At | |
Ixed (Tree a) # | |
Defined in Control.Lens.At | |
Ixed (Seq a) # | |
Defined in Control.Lens.At | |
Ord k => Ixed (Set k) # | |
Defined in Control.Lens.At | |
(Eq k, Hashable k) => Ixed (HashSet k) # | |
Defined in Control.Lens.At | |
Unbox a => Ixed (Vector a) # | |
Defined in Control.Lens.At | |
Storable a => Ixed (Vector a) # | |
Defined in Control.Lens.At | |
Prim a => Ixed (Vector a) # | |
Defined in Control.Lens.At | |
Ixed (Vector a) # | |
Defined in Control.Lens.At | |
Eq e => Ixed (e -> a) # | |
Defined in Control.Lens.At ix :: Index (e -> a) -> Traversal' (e -> a) (IxValue (e -> a)) # | |
a ~ a2 => Ixed (a, a2) # | |
Defined in Control.Lens.At ix :: Index (a, a2) -> Traversal' (a, a2) (IxValue (a, a2)) # | |
(IArray UArray e, Ix i) => Ixed (UArray i e) # | arr |
Defined in Control.Lens.At | |
Ix i => Ixed (Array i e) # | arr |
Defined in Control.Lens.At | |
Ord k => Ixed (Map k a) # | |
Defined in Control.Lens.At | |
(Eq k, Hashable k) => Ixed (HashMap k a) # | |
Defined in Control.Lens.At | |
(a ~ a2, a ~ a3) => Ixed (a, a2, a3) # | |
Defined in Control.Lens.At ix :: Index (a, a2, a3) -> Traversal' (a, a2, a3) (IxValue (a, a2, a3)) # | |
(a ~ a2, a ~ a3, a ~ a4) => Ixed (a, a2, a3, a4) # | |
Defined in Control.Lens.At ix :: Index (a, a2, a3, a4) -> Traversal' (a, a2, a3, a4) (IxValue (a, a2, a3, a4)) # | |
(a ~ a2, a ~ a3, a ~ a4, a ~ a5) => Ixed (a, a2, a3, a4, a5) # | |
Defined in Control.Lens.At ix :: Index (a, a2, a3, a4, a5) -> Traversal' (a, a2, a3, a4, a5) (IxValue (a, a2, a3, a4, a5)) # | |
(a ~ a2, a ~ a3, a ~ a4, a ~ a5, a ~ a6) => Ixed (a, a2, a3, a4, a5, a6) # | |
Defined in Control.Lens.At ix :: Index (a, a2, a3, a4, a5, a6) -> Traversal' (a, a2, a3, a4, a5, a6) (IxValue (a, a2, a3, a4, a5, a6)) # | |
(a ~ a2, a ~ a3, a ~ a4, a ~ a5, a ~ a6, a ~ a7) => Ixed (a, a2, a3, a4, a5, a6, a7) # | |
Defined in Control.Lens.At 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)) # | |
(a ~ a2, a ~ a3, a ~ a4, a ~ a5, a ~ a6, a ~ a7, a ~ a8) => Ixed (a, a2, a3, a4, a5, a6, a7, a8) # | |
Defined in Control.Lens.At 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)) # | |
(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) # | |
Defined in Control.Lens.At 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)) # |
iix :: Ixed m => Index m -> IndexedTraversal' (Index m) m (IxValue m) #
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
This class provides a simple Lens
that lets you view (and modify)
information about whether or not a container contains a given Index
.
contains :: Index m -> Lens' m Bool #
>>>
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]
icontains :: Contains m => Index m -> IndexedLens' (Index m) m Bool #
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]