Lens Families

Version on this page:1.2.3
LTS Haskell 13.23:1.2.3
Stackage Nightly 2019-05-26:1.2.3
Latest on Hackage:1.2.3

See all snapshots lens-family appears in

BSD-3-Clause licensed by Russell O'Connor

This package provides first class functional references. In addition to the usual operations of getting, setting and composition, plus integration with monad state, lens families provide some unique features:

  • Polymorphic updating

  • Traversals

  • Cast projection functions to read-only lenses

  • Cast "toList" functions to read-only traversals

  • Cast semantic editor combinators to modify-only traversals.


1.2.3 (Changes from 1.2.2)
* Bump dependency on containers

1.2.2 (Changes from 1.2.1)
* Added strict versions of assignments to Lens.Family2.State modules.
* Added strict versions of at' and intAt'.
* Min dependencies raised to take advantage of adjustF from Data.Map.

1.2.1 (Changes from 1.2.0)
* Bump dependency on transformers and mtl

1.2.0 (Changes from 1.1.0)
* Corrected associativity of ^. ^.. and ^? from right to left.

1.1.0 (Changes from 1.0.1)
* Some type synonym definitions have been altered, but should be equivalent.
* Removed Getting and Setting functors and instead use the equivalent standard functors Const and Identity.
* Renamed Setter to ASetter and generalized Setters to be a LensLike constrained to an "Identical" functor.
* Added the (<~) operator.
* Corrected the definition of ATraversal'

1.0.1 (Changes from 1.0.0)
* Bump dependency on transformers and mtl

1.0.0 (Changes from 0.1.0)
* added support for folds and traversals
* renamed all functions to be mostly compatible with the lexicon from lens.

0.1.0 (Changes from 0.0.1)
* added project and sec
* added <>= and <>~
* renamed functional modifier operators
* moving setting to Lens.Family2.Unchecked because one needs to verify the functor laws

0.0.1 (Changes from 0.0.0)
* Bump dependency on containers
* Fixed dependency on mtl
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