Couple of years ago I tried to write something in prolog. I thought about doing the classical syllogism about Socrates (the one about mortality) but in a sudden illumination I wanted to recreate a classical sketch from the movie Monty Python and the Holy Grail (1975).

So the requirements to “get” the jokes are that you are a geek, and that you love the Pythons (which is a syllogism by itself). Knowing some Prolog doesn’t hurt.

witch(X)  :- burns(X) , female(X).
burns(X)  :- wooden(X).
wooden(X) :- floats(X).
floats(X) :- sameweight(duck, X).

female(girl).
sameweight(duck,girl).