name: lens category: Data, Lenses version: 2.7 x-revision: 1 license: BSD3 cabal-version: >= 1.8 license-file: LICENSE author: Edward A. Kmett maintainer: Edward A. Kmett stability: provisional homepage: http://github.com/ekmett/lens/ bug-reports: http://github.com/ekmett/lens/issues copyright: Copyright (C) 2012 Edward A. Kmett synopsis: Lenses, Folds and Traversals description: This package comes \"Batteries Included\" with many useful lenses for the types commonly used from the Haskell Platform, and with tools for automatically generating lenses and isomorphisms for user-supplied data types. . The combinators in @Control.Lens@ provide a highly generic toolbox for composing families of getters, folds, isomorphisms, traversals, setters and lenses and their indexed variants. . An overview, with a large number of examples can be found in the README. . . More information on the care and feeding of lenses, including a brief tutorial and motivation for their types can be found on the lens wiki. . . A small game that manages its state using lenses can be found in the example folder. . . /Lenses, Folds and Traversals/ . The core of this hierarchy looks like: . <> . You can compose any two elements of the hierarchy above using (.) from the Prelude, and you can use any element of the hierarchy as any type it links to above it. . The result is their lowest upper bound in the hierarchy (or an error if that bound doesn't exist). . For instance: . * You can use any 'Traversal' as a 'Fold' or as a 'Setter'. . * The composition of a 'Traversal' and a 'Getter' yields a 'Fold'. . /Minimizing Dependencies/ . If you want to provide lenses and traversals for your own types in your own libraries, then you can do so without incurring a dependency on this (or any other) lens package at all. . e.g. for a data type: . > data Foo a = Foo Int Int a . You can define lenses such as . > -- bar :: Simple Lens (Foo a) Int > bar :: Functor f => (Int -> f Int) -> Foo a -> f Foo a > bar f (Foo a b c) = fmap (\a' -> Foo a' b c) (f a) . > -- baz :: Lens (Foo a) (Foo b) a b > quux :: Functor f => (a -> f b) -> Foo a -> f (Foo b) > quux f (Foo a b c) = fmap (Foo a b) (f c) . without the need to use any type that isn't already defined in the @Prelude@. . And you can define a traversal of multiple fields with 'Control.Applicative.Applicative': . > -- traverseBarAndBaz :: Simple Traversal (Foo a) Int > traverseBarAndBaz :: Applicative f => (Int -> f Int) -> Foo a -> f (Foo a) > traverseBarAndBaz f (Foo a b c) = Foo <$> f a <*> f b <*> pure c . What is provided in this library is a number of stock lenses and traversals for common haskell types, a wide array of combinators for working them, and more exotic functionality, (e.g. getters, setters, indexed folds, isomorphisms). build-type: Simple tested-with: GHC == 7.4.1, GHC == 7.6.0, GHC == 7.7.20120822, GHC == 7.7.20120830 extra-source-files: .travis.yml .ghci .gitignore .vim.custom config examples/LICENSE examples/lens-examples.cabal examples/Pong.hs examples/Plates.hs README.markdown CHANGELOG.markdown source-repository head type: git location: git://github.com/ekmett/lens.git -- Enable benchmarking against Neil Mitchell's uniplate library for comparative performance analysis. Defaults to being turned off to avoid -- the extra dependency. -- -- > cabal configure --enable-benchmarks -fbenchmark-uniplate && cabal build && cabal bench flag benchmark-uniplate default: False manual: True -- Enable template haskell. Disable this at your own risk and for testing only. -- -- cabal configure -f-template-haskell is an /unsuppported/ configuration. -- -- Clients of this library can and should expect this to be turned on. flag template-haskell default: True manual: True -- Generate inline pragmas when using template-haskell. This defaults to enabled, but you can -- -- > cabal install lens -f-inlining -- -- to shut it off to benchmark the relative performance impact, or as last ditch effort to address compile -- errors resulting from the myriad versions of template-haskell that all purport to be 2.8. flag inlining manual: True default: True -- Some 7.6.1-rc1 users report their TH still uses old style inline pragmas. This lets them turn on inlining. flag old-inline-pragmas default: False manual: True library -- broken package-version due to missing module "Control.Lens.Combinators" build-depends: base<0 build-depends: base >= 4.3 && < 5, bytestring >= 0.9.1.10 && < 0.11, comonad == 3.0.*, comonad-transformers == 3.0.*, comonads-fd == 3.0.*, containers >= 0.4.2 && < 0.6, hashable == 1.1.*, mtl >= 2.1.1 && < 2.2, text >= 0.11 && < 0.12, transformers >= 0.3 && < 0.4, unordered-containers >= 0.2 && < 0.3 exposed-modules: Control.Exception.Lens Control.Lens Control.Lens.Action Control.Lens.Fold Control.Lens.Getter Control.Lens.Indexed Control.Lens.IndexedGetter Control.Lens.IndexedFold Control.Lens.IndexedLens Control.Lens.IndexedSetter Control.Lens.IndexedTraversal Control.Lens.Internal Control.Lens.Iso Control.Lens.Isomorphic Control.Lens.Plated Control.Lens.Representable Control.Lens.Setter Control.Lens.Traversal Control.Lens.Tuple Control.Lens.Type Control.Lens.WithIndex Control.Lens.Zoom Data.Bits.Lens Data.ByteString.Lens Data.ByteString.Strict.Lens Data.ByteString.Lazy.Lens Data.Complex.Lens Data.Data.Lens Data.Dynamic.Lens Data.HashSet.Lens Data.IntSet.Lens Data.List.Lens Data.Monoid.Lens Data.Sequence.Lens Data.Set.Lens Data.Text.Lens Data.Text.Strict.Lens Data.Text.Lazy.Lens Data.Tree.Lens Data.Typeable.Lens if flag(template-haskell) build-depends: template-haskell >= 2.4 && < 2.9 exposed-modules: Control.Lens.TH Language.Haskell.TH.Lens else cpp-options: -DDISABLE_TEMPLATE_HASKELL -- platform build-depends: array >= 0.3.0.2 && < 0.5 exposed-modules: Data.Array.Lens build-depends: filepath >= 1.2.0.0 && < 1.4 exposed-modules: System.FilePath.Lens build-depends: parallel >= 3.1.0.1 && < 3.3 exposed-modules: Control.Parallel.Strategies.Lens Control.Seq.Lens if impl(ghc>=7.6.0.20120810) if flag(old-inline-pragmas) cpp-options: -DOLD_INLINE_PRAGMAS if !flag(inlining) cpp-options: -DOMIT_INLINING if impl(ghc>=7.4) other-extensions: Trustworthy build-depends: ghc-prim exposed-modules: GHC.Generics.Lens ghc-options: -Wall -fwarn-tabs -O2 -fdicts-cheap -funbox-strict-fields hs-source-dirs: src -- Verify the results of the examples test-suite doctests type: exitcode-stdio-1.0 main-is: doctests.hs build-depends: base, directory >= 1.0 && < 1.3, doctest >= 0.8 && <= 0.9, filepath ghc-options: -Wall -threaded if impl(ghc<7.6.1) ghc-options: -Werror hs-source-dirs: tests -- Verify that Template Haskell expansion works test-suite templates type: exitcode-stdio-1.0 main-is: templates.hs build-depends: base, lens ghc-options: -Wall -threaded if impl(ghc<7.6.1) ghc-options: -Werror hs-source-dirs: tests -- Verify the properties of lenses with QuickCheck test-suite properties type: exitcode-stdio-1.0 main-is: properties.hs build-depends: base, lens, QuickCheck >= 2.4 && < 2.6, transformers ghc-options: -w -threaded hs-source-dirs: tests test-suite hunit type: exitcode-stdio-1.0 main-is: hunit.hs build-depends: base, containers, HUnit == 1.2.*, lens, mtl, test-framework == 0.6.*, test-framework-hunit == 0.2.*, test-framework-th == 0.2.* ghc-options: -w -threaded hs-source-dirs: tests -- Basic benchmarks for the uniplate-style combinators benchmark plated type: exitcode-stdio-1.0 main-is: plated.hs build-depends: base, comonad, criterion, deepseq, ghc-prim, lens, transformers ghc-options: -Wall -O2 -threaded hs-source-dirs: benchmarks if flag(benchmark-uniplate) build-depends: uniplate >= 1.6.7 && < 1.7 cpp-options: -DBENCHMARK_UNIPLATE