There are a pair of research languages called Harmony and Boomerang [1] that does this with what they call "lenses". There are also some easy-reading introducto

There are a pair of research languages called Harmony and Boomerang [1] that does this with what they call "lenses". There are also some easy-reading introductory slides [2,3]. [1] http://www.seas.upenn.edu/~harmony/ http://www.seas.upenn.edu/~harmony/ [2] http://www.cis.upenn.edu/~bcpierce/papers/lenses-etapsslides.pdf http://www.cis.upenn.edu/~bcpierce/papers/lenses-etapsslides... [3] http://www.cis.upenn.edu/~bcpierce/papers/harmful-mfps.pdf http://www.cis.upenn.edu/~bcpierce/papers/harmful-mfps.pdf