What are functional lenses? http://www.haskellforall.com/2012/01/haskell-for-mainstream-programmers_28.html http://www.haskellforall.com/2012/01/haskell-for-ma

What are functional lenses? http://www.haskellforall.com/2012/01/haskell-for-mainstream-programmers_28.html http://www.haskellforall.com/2012/01/haskell-for-mainstream-... http://stackoverflow.com/questions/8307370/functional-lenses http://stackoverflow.com/questions/8307370/functional-lenses