fclabels: First class accessor labels implemented as lenses.
This package provides first class labels that can act as bidirectional record fields. The labels can be derived automatically using Template Haskell which means you don't have to write any boilerplate yourself. The labels are implemented as lenses and are fully composable. Lenses can be used to get, set and modify parts of a data type in a consistent way.
See Data.Label for an introductory explanation or see the introductory blog post at http://fvisser.nl/post/2013/okt/1/fclabels-2.0.html
Total and partial lenses
Internally lenses do not used Haskell functions directly, but are implemented as categories. Categories allow the lenses to be run in custom computational contexts. This approach allows us to make partial lenses that point to fields of multi-constructor datatypes in an elegant way.
See Data.Label.Partial for the use of partial labels.
Monomorphic and polymorphic lenses
We have both polymorphic and monomorphic lenses. Polymorphic lenses allow updates that change the type. The types of polymorphic lenses are slightly more verbose than their monomorphic counterparts, but their usage is similar. Because monomorphic lenses are built by restricting the types of polymorphic lenses they are essentially the same and can be freely composed with eachother.
To simplify working with labels we supply both a set of labels for Haskell's base types, like lists, tuples, Maybe and Either, and we supply a set of combinators for working with labels for values in the Reader and State monad.
Changelog from 2.0.2 to 188.8.131.52
- Support for GHC 7.10 by widening TH dependencies.
|Versions [faq]||0.1, 0.1.2, 0.2.0, 0.3.0, 0.4.0, 0.4.1, 0.4.2, 0.4.2.1, 0.9.0, 0.9.1, 0.11.0, 0.11.1, 0.11.1.1, 0.11.2, 1.0, 1.0.1, 1.0.2, 1.0.3, 1.0.4, 1.0.5, 1.1.0, 184.108.40.206, 220.127.116.11, 18.104.22.168, 22.214.171.124, 1.1.2, 1.1.3, 1.1.4, 126.96.36.199, 188.8.131.52, 184.108.40.206, 1.1.5, 1.1.6, 1.1.7, 220.127.116.11, 2.0, 18.104.22.168, 22.214.171.124, 126.96.36.199, 188.8.131.52, 184.108.40.206, 2.0.1, 220.127.116.11, 2.0.2, 18.104.22.168, 22.214.171.124, 126.96.36.199, 188.8.131.52, 2.0.3, 184.108.40.206, 220.127.116.11, 18.104.22.168, 2.0.4, 2.0.5|
|Dependencies||base (<5), mtl (>=1.0 && <2.3), template-haskell (>=2.8 && <2.11), transformers (>=0.2 && <0.5) [details]|
|Author||Sebastiaan Visser, Erik Hesselink, Chris Eidhof, Sjoerd Visscher with lots of help and feedback from others.|
|Maintainer||Sebastiaan Visser <firstname.lastname@example.org>|
|Revised||Revision 1 made by HerbertValerioRiedel at 2015-01-07T08:13:33Z|
|Source repo||head: git clone git://github.com/sebastiaanvisser/fclabels.git|
|Uploaded||by SebastiaanVisser at 2015-01-06T14:31:59Z|
|Distributions||Arch:2.0.5, Debian:22.214.171.124, Fedora:2.0.5, LTSHaskell:126.96.36.199, NixOS:2.0.5, Stackage:188.8.131.52|
|Downloads||64775 total (354 in the last 30 days)|
|Rating||2.25 (votes: 2) [estimated by Bayesian average]|
Docs available [build log]
Last success reported on 2015-01-06 [all 1 reports]
- fclabels-184.108.40.206.tar.gz [browse] (Cabal source package)
- Package description (revised from the package)
Note: This package has metadata revisions in the cabal description newer than included in the tarball. To unpack the package including the revisions, use 'cabal get'.
For package maintainers and hackage trustees