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GHC 9.10.3 · lts/ghc-9.10.x · c74966e · 2026-09-27

Modulelens-5.3.5Haskell2010

Data.Vector.Lens

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

  • 5 values
  • Packagelens-5.3.5
  • Exports5
  • LanguageHaskell2010
  • LicenceBSD-2-Clause
  • SourceLens.hs

Isomorphisms

2 declarations
valuevector
  1. :: (Profunctor p, Functor f)
  2. => p (Vector a) (f (Vector b))
  3. -> p [a] (f [b])
#

Convert a list to a Vector (or back)

Example1 expression
[1,2,3] ^. vector == Vector.fromList [1,2,3]True
Example1 expression
[1,2,3] ^. vector . from vector[1,2,3]
Example1 expression
Vector.fromList [0,8,15] ^. from vector . vector == Vector.fromList [0,8,15]True

Lenses

1 declaration
valuesliced
  1. :: Int

    i starting index

  2. -> Int

    n length

  3. -> Lens' (Vector a) (Vector 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.

Example1 expression
Vector.fromList [1..10] ^. sliced 2 5 == Vector.fromList [3,4,5,6,7]True
Example1 expression
(Vector.fromList [1..10] & sliced 2 5 . mapped .~ 0) == Vector.fromList [1,2,0,0,0,0,0,8,9,10]True

Traversal of individual indices

1 declaration
valueordinals :: [Int] -> IndexedTraversal' Int (Vector a) a
#

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

Example1 expression
toListOf (ordinals [1,3,2,5,9,10]) $ Vector.fromList [2,4..40][4,8,6,12,20,22]