devel:languages:haskell Haskell Development Project for openSUSE:Factory Haskell is a standardized purely functional programming language with non-strict semantics, named after the logician Haskell Curry. It is one of the more popular functional languages, and the lazy functional language on which the most research is being performed. This is a development project for openSUSE:Factory that contains only the most essential tools to set up a Haskell development environment, like ghc, cabal-install, and their respective dependencies. This repository is supposed to be small and manageable. https://download.opensuse.org/repositories/devel:/languages:/haskell/openSUSE_Factory_PowerPC_standard/ openSUSE:Factory:PowerPC openSUSE Factory PowerPC This is a project clone to build entire openSUSE:Factory for the PowerPC (PPC) architecture https://download.opensuse.org/repositories/openSUSE:/Factory:/PowerPC/standard/ openSUSE:Factory The next openSUSE distribution Any user who wishes to have the newest packages that include, but are not limited to, the Linux kernel, SAMBA, git, desktops, office applications and many other packages, will want Tumbleweed. Tumbleweed appeals to Power Users, Software Developers and openSUSE Contributors. If you require the latest software stacks and Integrated Development Environment or need a stable platform closest to bleeding edge Linux, Tumbleweed is the best choice for you. Staging dashboard is located at: https://build.opensuse.org/staging_workflows/openSUSE:Factory List of known devel projects: https://build.opensuse.org/package/view_file/openSUSE:Factory:Staging/dashboard/devel_projects Have a look at http://en.opensuse.org/Portal:Factory for more details. https://download.opensuse.org/repositories/openSUSE:/Factory/ports/ ghc-lens Lenses, Folds and Traversals 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 <https://github.com/ekmett/lens#lens-lenses-folds-and-traversals README>. An introductory video on the style of code used in this library by Simon Peyton Jones is available from <http://skillsmatter.com/podcast/scala/lenses-compositional-data-access-and-manipulation Skills Matter>. A video on how to use lenses and how they are constructed is available on <http://youtu.be/cefnmjtAolY?hd=1 youtube>. Slides for that second talk can be obtained from <http://comonad.com/haskell/Lenses-Folds-and-Traversals-NYC.pdf comonad.com>. More information on the care and feeding of lenses, including a brief tutorial and motivation for their types can be found on the <https://github.com/ekmett/lens/wiki lens wiki>. A small game of 'pong' and other more complex examples that manage their state using lenses can be found in the <https://github.com/ekmett/lens/blob/master/examples/ example folder>. /Lenses, Folds and Traversals/ With some signatures simplified, the core of the hierarchy of lens-like constructions looks like: <<http://i.imgur.com/ALlbPRa.png>> <https://raw.githubusercontent.com/ekmett/lens/master/images/Hierarchy.png (Local Copy)> 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).