GenericPretty is a Haskell library that supports automatic derivation of pretty printing functions on user defined data types.
The form of geenrics used is based on that introduced in the paper: Magalhaes, Dijkstra, Jeuring, and Loh, A Generic Deriving Mechanism for Haskell, 3'rd ACM Symposium on Haskell, pp. 37-48, September 2010, http://dx.doi.org/10.1145/1863523.1863529. Changes from the original paper in the GHC implementation are described here: http://www.haskell.org/haskellwiki/GHC.Generics#Changes_from_the_paper.
This package requires the use of the new GHC.Generics features http://www.haskell.org/haskellwiki/GHC.Generics, present from GHC 7.2. Use of these features is indicated by the DeriveGeneric pragma. or the flag -XDeriveGeneric.
Pretty printing produces values of type Text.PrettyPrint.Doc, using the Text.PrettyPrint library http://www.haskell.org/ghc/docs/latest/html/libraries/pretty-126.96.36.199/Text-PrettyPrint.html.
The output provided is a pretty printed version of that provided by Prelude.show. That is, rendering the document provided by this pretty printer yields an output identical to that of Prelude.show, except for extra whitespace.
For information about the functions exported by the package please see the API linked further down this page. For examples of usage, both basic and more complex see the README file and the haskell source code files in the TestSuite folder, both included in the package. Finally for installation instructions also see the README file or this page: http://www.haskell.org/haskellwiki/Cabal/How_to_install_a_Cabal_package