@hackage between0.9.0.0

It turns out that this combinator

f ~@~ g = (f .) . (. g)

is a powerful thing. It was abstracted from following (commonly used) pattern f . h . g where f and g are fixed.

This library not only defines ~@~ combinator, but also a some derived combinators that can help us to easily define a lot of things including lenses. See lens package for detais on what lenses are.