A while back I developed an approach to this in haskell; the idea is to use a logic monad transformer ("Backtracking, Interleaving, and Terminating Monad Transf

A while back I developed an approach to this in haskell; the idea is to use a logic monad transformer ("Backtracking, Interleaving, and Terminating Monad Transformers" 2005), working at a monad which implements a type class 'Costly' with a single method 'cost'. The implementation of 'cost' can terminate branches of the logic program or transform it in other ways. Then polymorphism over this monad accomplishes the generalization of the logic program over different search strategies.