natural transformations; documentation

 A natural transformation transforms a container f a into another
 container g a. Natural transformations act as functor morphisms
 in category theory.
 .
 Technically, f and g should be functors, any correctly-shaped
 structure is allowed.
 .
 This package provides the documentation for a library for the Haskell
 programming language.
 See http://www.haskell.org/ for more information on Haskell.