# # spec file for package lens # # Copyright (c) 2018 SUSE LINUX GmbH, Nuernberg, Germany. # # All modifications and additions to the file contributed by third parties # remain the property of their copyright owners, unless otherwise agreed # upon. The license for this file, and modifications and additions to the # file, is the same license as for the pristine package itself (unless the # license for the pristine package is not an Open Source License, in which # case the license is the MIT License). An "Open Source License" is a # license that conforms to the Open Source Definition (Version 1.9) # published by the Open Source Initiative. # Please submit bugfixes or comments via http://bugs.opensuse.org/ # %global pkg_name lens %bcond_with tests Name: %{pkg_name} Version: 4.15.4 Release: 0 Summary: Lenses, Folds and Traversals License: BSD-2-Clause Group: Development/Libraries/Haskell URL: https://hackage.haskell.org/package/%{name} Source0: https://hackage.haskell.org/package/%{name}-%{version}/%{name}-%{version}.tar.gz BuildRequires: ghc-Cabal-devel BuildRequires: ghc-array-devel BuildRequires: ghc-base-orphans-devel BuildRequires: ghc-bifunctors-devel BuildRequires: ghc-bytestring-devel BuildRequires: ghc-cabal-doctest-devel BuildRequires: ghc-call-stack-devel BuildRequires: ghc-comonad-devel BuildRequires: ghc-containers-devel BuildRequires: ghc-contravariant-devel BuildRequires: ghc-distributive-devel BuildRequires: ghc-exceptions-devel BuildRequires: ghc-filepath-devel BuildRequires: ghc-free-devel BuildRequires: ghc-hashable-devel BuildRequires: ghc-kan-extensions-devel BuildRequires: ghc-mtl-devel BuildRequires: ghc-parallel-devel BuildRequires: ghc-profunctors-devel BuildRequires: ghc-reflection-devel BuildRequires: ghc-rpm-macros BuildRequires: ghc-semigroupoids-devel BuildRequires: ghc-semigroups-devel BuildRequires: ghc-tagged-devel BuildRequires: ghc-template-haskell-devel BuildRequires: ghc-text-devel BuildRequires: ghc-th-abstraction-devel BuildRequires: ghc-transformers-compat-devel BuildRequires: ghc-transformers-devel BuildRequires: ghc-unordered-containers-devel BuildRequires: ghc-vector-devel BuildRequires: ghc-void-devel %if %{with tests} BuildRequires: ghc-HUnit-devel BuildRequires: ghc-QuickCheck-devel BuildRequires: ghc-deepseq-devel BuildRequires: ghc-directory-devel BuildRequires: ghc-doctest-devel BuildRequires: ghc-generic-deriving-devel BuildRequires: ghc-nats-devel BuildRequires: ghc-simple-reflect-devel BuildRequires: ghc-test-framework-devel BuildRequires: ghc-test-framework-hunit-devel BuildRequires: ghc-test-framework-quickcheck2-devel BuildRequires: ghc-test-framework-th-devel %endif %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 . An introductory video on the style of code used in this library by Simon Peyton Jones is available from . A video on how to use lenses and how they are constructed is available on . Slides for that second talk can be obtained from . More information on the care and feeding of lenses, including a brief tutorial and motivation for their types can be found on the . A small game of 'pong' and other more complex examples that manage their state using lenses can be found in the . /Lenses, Folds and Traversals/ With some signatures simplified, the core of the hierarchy of lens-like constructions 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 linked 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 :: 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) > -- quux :: 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 :: 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). %package -n ghc-%{name} Summary: Haskell %{name} library Group: System/Libraries %description -n ghc-%{name} This package provides the Haskell %{name} shared library. %package -n ghc-%{name}-devel Summary: Haskell %{name} library development files Group: Development/Libraries/Haskell Requires: ghc-%{name} = %{version}-%{release} Requires: ghc-compiler = %{ghc_version} Requires(post): ghc-compiler = %{ghc_version} Requires(postun): ghc-compiler = %{ghc_version} %description -n ghc-%{name}-devel This package provides the Haskell %{name} library development files. %prep %setup -q %build %ghc_lib_build %install %ghc_lib_install %check %cabal_test %post -n ghc-%{name}-devel %ghc_pkg_recache %postun -n ghc-%{name}-devel %ghc_pkg_recache %files %license LICENSE %doc AUTHORS.markdown CHANGELOG.markdown README.markdown examples %files -n ghc-%{name} -f ghc-%{name}.files %license LICENSE %files -n ghc-%{name}-devel -f ghc-%{name}-devel.files %doc AUTHORS.markdown CHANGELOG.markdown README.markdown examples %changelog