lens-4.11.1: Lenses, Folds and Traversals

Copyright(C) 2012-2015 Edward Kmett
LicenseBSD-style (see the file LICENSE)
MaintainerEdward Kmett <ekmett@gmail.com>
Safe HaskellTrustworthy




This module provides lenses and traversals for working with generic vectors.



toVectorOf :: Vector v a => Getting (Endo [a]) s a -> s -> v a Source

Similar to toListOf, but returning a Vector.

>>> toVectorOf both (8,15) :: Vector.Vector Int
fromList [8,15]


forced :: Vector v a => Iso' (v a) (v a) Source

Convert a Vector to a version that doesn't retain any extra memory.

vector :: (Vector v a, Vector v b) => Iso [a] [b] (v a) (v b) Source

Convert a list to a Vector (or back.)

>>> [1,2,3] ^. vector :: Vector.Vector Int
fromList [1,2,3]
>>> Vector.fromList [0,8,15] ^. from vector

asStream :: (Vector v a, Vector v b) => Iso (v a) (v b) (Stream a) (Stream b) Source

Convert a Vector to a finite Stream (or back.)

asStreamR :: (Vector v a, Vector v b) => Iso (v a) (v b) (Stream a) (Stream b) Source

Convert a Vector to a finite Stream from right to left (or back.)

cloned :: Vector v a => Iso' (v a) (New v a) Source

Convert a Vector back and forth to an initializer that when run produces a copy of the Vector.

converted :: (Vector v a, Vector w a, Vector v b, Vector w b) => Iso (v a) (v b) (w a) (w b) Source

Different vector implementations are isomorphic to each other.


sliced Source


:: Vector v a 
=> Int

i starting index

-> Int

n length

-> Lens' (v a) (v a) 

sliced i n provides a Lens that edits the n elements starting at index i from a Lens.

This is only a valid Lens if you do not change the length of the resulting Vector.

Attempting to return a longer or shorter vector will result in violations of the Lens laws.

>>> Vector.fromList [1..10] ^. sliced 2 5
fromList [3,4,5,6,7]
>>> Vector.fromList [1..10] & sliced 2 5 . mapped .~ 0
fromList [1,2,0,0,0,0,0,8,9,10]

Traversal of individual indices

ordinals :: Vector v a => [Int] -> IndexedTraversal' Int (v a) a Source

This Traversal will ignore any duplicates in the supplied list of indices.

>>> toListOf (ordinals [1,3,2,5,9,10]) $ Vector.fromList [2,4..40]

vectorIx :: Vector v a => Int -> Traversal' (v a) a Source

Like ix but polymorphic in the vector type.

vectorTraverse :: (Vector v a, Vector w b) => IndexedTraversal Int (v a) (w b) a b Source

Indexed vector traversal for a generic vector.