Slides: http://comonad.com/haskell/Lenses-Folds-and-Traversals-NYC.pdf This was a talk I gave at the second New York Haskell User Group Meeting (http://www.meetup.com/NY-Haskell/) on the new lens library, which provides a highly composable toolbox for accessing and modifying multiple parts of data structures. Starting with building blocks such as fmap and (.), we build up combinators suitable ...