natural-transformation-0.3: README.md

# natural-transformation [![Hackage version](https://img.shields.io/hackage/v/natural-transformation.svg?style=flat)](http://hackage.haskell.org/package/natural-transformation) [![Build Status](https://img.shields.io/travis/ku-fpg/natural-transformation.svg?style=flat)](https://travis-ci.org/ku-fpg/natural-transformation)

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, but we allow any correctly-shaped structure.