From simple beginnings, starting with building blocks such as fmap and (.), we will build up combinators suitable for working with a wide array of data structures. These generalize the notions you already know how to use into a form that is easier to compose, and simultaneously allow them to be used for monomorphic containers such as Data.Text. All without compromising on your ability to reason about

The first NY Haskell Users Group meetup was a great success -- with roughly sixty attendees and conversations that stretched far too late for a weekday night. Video and slides are available for both the Practical Data Processing and Cloud Haskell talks: Video: http://vimeo.com/53906049 Slides on Practical Data Processing: http://gbaz.github.com/slides/PracticalData-11-2012.pdf Slides on Cloud Haskell: http://gbaz.github.com/slides/cloud-11-2012.html Source for Cloud Haskell: https://github.com/gbaz/slides/blob/gh-pages/cloud-11-2012.lhs We expect our next meetup will be equally exciting, at a bare minimum. We're actively seeking cool talks and presentations. If you're not a New York local, but may be passing through or are in the tri-state area or thereabouts, and would like to present some code or research with even tangentially real-world implications to an informed and appreciated audience, please do get in touch :-) Also, there will be a NY tech holiday party on December 11th, which we are organizing along with other NY technology and PL groups. Details are available at the on the meetup site: http://www.meetup.com/NY-Haskell/. Finally, at some point, we will probably cease to spam -cafe with announcements of all our events, so even if you can't make it to the next few ones, registering at the meetup site is the best way to stay on top of what we will have planned. - - - - Lenses, Folds, and Traversals presented by Edward Kmett Wednesday, December 12, 2012 7:00 PM To 9:00 PM Pivotal Labs, 841 Broadway New York, NY (8th Floor) RSVP: http://www.meetup.com/NY-Haskell/ Edward Kmett will introduce his lens library, which provides a highly composable toolbox for accessing and modifying multiple parts of data structures. them using laws! Once we've built up some foundations, we'll do a bit of a deep dive, exploring consequences of this design. We will discuss the efficient generic programming programming framework exported by lens, and type-safe Traversal-based zippers. Familiarity with the Applicative and Traversable classes from the Haskell base libraries will be helpful (links provided below), but a basic understanding of the concepts will be introduced we go along. Attendees should expect to be gobsmacked with a newfound appreciation for the power of a little (or a lot of) abstraction. Useful (but not mandatory) references: The lens library and documentation: http://hackage.haskell.org/package/lens A previous, more introductory talk on how to use the lenses Edward Kmett wrote for the scalaz in the Scala programming language: https://www.youtube.com/watch?v=efv0SQNde5Q The original Applicative paper: http://www.soi.city.ac.uk/~ross/papers/Applicative.pdf Lots of information on Traversable: http://www.cs.ox.ac.uk/jeremy.gibbons/publications/iterator.pdf A write-up of this talk, as presented at the Bay Area Haskell Users Group: http://google-opensource.blogspot.com/2012/10/lenses-folds-and-traversals-ha...