a tiny part of the lens library with no dependencies; documentation

 This is an extract from the lens package with no dependencies. It's not a toy
 lenses library, unsuitable for “real world”, but merely a small one. It is
 compatible with lens, and should have same performance. It also has better
 documentation.
 .
 This package provides the documentation for a library for the Haskell
 programming language.
 See http://www.haskell.org/ for more information on Haskell.