haskell@gentoo.org Gentoo Haskell 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. ( ) For optimal first-class support use the @lens-family@ package with rank 2 / rank N polymorphism. "Lens.Family.Clone" allows for first-class support of lenses and traversals for those who require Haskell 98.