Copyright | (C) 2012-15 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 |
- 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
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
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
type Index ByteString = Int Source | |
type Index ByteString = Int64 Source | |
type Index IntSet = Int Source | |
type Index Text = Int Source | |
type Index Text = Int64 Source | |
type Index [a] = Int Source | |
type Index (Identity a) = () Source | |
type Index (Complex a) = Int Source | |
type Index (Maybe a) = () Source | |
type Index (IntMap a) = Int Source | |
type Index (Set a) = a Source | |
type Index (Tree a) = [Int] Source | |
type Index (Seq a) = Int Source | |
type Index (NonEmpty a) = Int Source | |
type Index (HashSet a) = a Source | |
type Index (Vector a) = Int Source | |
type Index (Vector a) = Int Source | |
type Index (Vector a) = Int Source | |
type Index (Vector a) = Int Source | |
type Index (e -> a) = e Source | |
type Index (a, b) = Int Source | |
type Index (UArray i e) = i Source | |
type Index (Array i e) = i Source | |
type Index (Map k a) = k Source | |
type Index (HashMap k a) = k Source | |
type Index (a, b, c) = Int Source | |
type Index (a, b, c, d) = Int Source | |
type Index (a, b, c, d, e) = Int Source | |
type Index (a, b, c, d, e, f) = Int Source | |
type Index (a, b, c, d, e, f, g) = Int Source | |
type Index (a, b, c, d, e, f, g, h) = Int Source | |
type Index (a, b, c, d, e, f, g, h, i) = Int Source |
type family IxValue m :: * Source
type IxValue ByteString = Word8 Source | |
type IxValue ByteString = Word8 Source | |
type IxValue IntSet = () Source | |
type IxValue Text = Char Source | |
type IxValue Text = Char Source | |
type IxValue [a] = a Source | |
type IxValue (Identity a) = a Source | |
type IxValue (Maybe a) = a Source | |
type IxValue (IntMap a) = a Source | |
type IxValue (Set k) = () Source | |
type IxValue (Tree a) = a Source | |
type IxValue (Seq a) = a Source | |
type IxValue (NonEmpty a) = a Source | |
type IxValue (HashSet k) = () Source | |
type IxValue (Vector a) = a Source | |
type IxValue (Vector a) = a Source | |
type IxValue (Vector a) = a Source | |
type IxValue (Vector a) = a Source | |
type IxValue (e -> a) = a Source | |
type IxValue (a, a2) = a Source |
|
type IxValue (UArray i e) = e Source | |
type IxValue (Array i e) = e Source | |
type IxValue (Map k a) = a Source | |
type IxValue (HashMap k a) = a Source | |
type IxValue (a, a2, a3) = a Source |
|
type IxValue (a, a2, a3, a4) = a Source |
|
type IxValue (a, a2, a3, a4, a5) = a Source |
|
type IxValue (a, a2, a3, a4, a5, a6) = a Source |
|
type IxValue (a, a2, a3, a4, a5, a6, a7) = a Source |
|
type IxValue (a, a2, a3, a4, a5, a6, a7, a8) = a Source |
|
type IxValue (a, a2, a3, a4, a5, a6, a7, a8, a9) = a Source |
|
This 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
.
ix :: Index m -> Traversal' m (IxValue m) Source
This 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
.
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
Ixed ByteString Source | |
Ixed ByteString Source | |
Ixed IntSet Source | |
Ixed Text Source | |
Ixed Text Source | |
Ixed [a] Source | |
Ixed (Identity a) Source | |
Ixed (Maybe a) Source | |
Ixed (IntMap a) Source | |
Ord k => Ixed (Set k) Source | |
Ixed (Tree a) Source | |
Ixed (Seq a) Source | |
Ixed (NonEmpty a) Source | |
(Eq k, Hashable k) => Ixed (HashSet k) Source | |
Ixed (Vector a) Source | |
Prim a => Ixed (Vector a) Source | |
Storable a => Ixed (Vector a) Source | |
Unbox a => Ixed (Vector a) Source | |
Eq e => Ixed (e -> a) Source | |
(~) * a a2 => Ixed (a, a2) Source | |
(IArray UArray e, Ix i) => Ixed (UArray i e) Source | arr |
Ix i => Ixed (Array i e) Source | arr |
Ord k => Ixed (Map k a) Source | |
(Eq k, Hashable k) => Ixed (HashMap k a) Source | |
((~) * a a2, (~) * a a3) => Ixed (a, a2, a3) Source | |
((~) * a a2, (~) * a a3, (~) * a a4) => Ixed (a, a2, a3, a4) Source | |
((~) * a a2, (~) * a a3, (~) * a a4, (~) * a a5) => Ixed (a, a2, a3, a4, a5) Source | |
((~) * a a2, (~) * a a3, (~) * a a4, (~) * a a5, (~) * a a6) => Ixed (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 | |
((~) * a a2, (~) * a a3, (~) * a a4, (~) * a a5, (~) * a a6, (~) * a a7, (~) * a a8) => Ixed (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 |
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
This class provides a simple Lens
that lets you view (and modify)
information about whether or not a container contains a given Index
.
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]