data-lens-light

This is a minimalistic lens library, based on data-lens.

The main differences from data-lens are:

• reduced API
• minimal set of dependencies
• data-lens, data-lens-fd and data-lens-template exported through a single
  module in a single package
• MonadState combinators return ()
• strict MonadState combinators force the whole state, too

(The above list may be not exhaustive. Compatibility with data-lens is not a goal.)