FRIL

The FRIL language (Fuzzy Relation Inference Language) combines logic programming with uncertainity. FRIL combines support for classical logic with support for fuzzy logic and probability unified by mass assingments. FRIL has a list based syntax so in a way it is a dialect of Lisp:

(less-than
  (1 2)
  (2 3)
  (3 4))

FRIL supports both discrete and continuous fuzzy sets each with their own syntactic representations. The extension of classical logic with fuzzy sets makes FRIL a much more general and powerful language then Prolog.