Forward difference
You are encouraged to solve this task according to the task description, using any language you may know.
Provide code that produces a list of numbers which is the n-th order forward difference, given a non-negative integer (specifying the order) and a list of numbers. See Wolfram MathWorld:Forward Difference.
J
Of the many ways to code this in J, a particularly clear and concise solution is:
fd=: (}. - }:) ^: