Forward-mode automatic differentiation is always fun to see because of the power but simplicity of the method. Any language with pattern matching makes it almos

Forward-mode automatic differentiation is always fun to see because of the power but simplicity of the method. Any language with pattern matching makes it almost trivial to implement. Although, I'm rarely interested in <such and such> in <n> lines of <language>. The more interesting things are overall conciseness with regards to the problem, the expressiveness, and the clarity that the code produces.