This package provides first-class functional references.
 In addition to the usual operations of getting, setting and
 composition, plus integration with the state monad, 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.
 .
 This package provides the documentation for a library for the Haskell
 programming language.
 See http://www.haskell.org/ for more information on Haskell.