Lennart has a nice writeup on automatic differentiation in Haskell. I keep trying to come up with a reason to learn more about Haskell, and examples like this (which are difficult or at least less understandable in C or C++) go quite some way in convincing me that I should invest the time to understand how lazy, functional, polymorphic languages like Haskell can change the way I write programs.

[tags]Programming.Haskell, Automatic Differentiation[/tags]