The beauty of this is that a constraint solver (over finite domains, Boolean values, sets etc.) blends in completely seamlessly into the way Prolog works.
From the perspective of Prolog and its users, a constraint solver is simply available just like any other predicate! All the internal reasoning a constraint solver performs is completely abstracted away. The only interface is typically a few Prolog predicates that let you access the features of the solver by stating what must hold about the involved variables.
So, to use a constraint solver in Prolog, you simply use the predicates it provides, just as you would use any other Prolog predicate. In the example above, I am using the constraint (#=)/2, which is a predicate that is true iff its arguments evaluate to the same integer.
From the perspective of implementors, Prolog is a great implementation language for constraint solvers due to its built-in search and backtracking mechanisms. It also allows you to use the standardized Prolog syntax that many users are already familiar with, instead of having to devise yet another modeling language on top of your solver.
Thus, I would describe the relation as a natural symbiosis: It is natural to use constraint solvers in Prolog, and natural to implement them in Prolog.
From the perspective of Prolog and its users, a constraint solver is simply available just like any other predicate! All the internal reasoning a constraint solver performs is completely abstracted away. The only interface is typically a few Prolog predicates that let you access the features of the solver by stating what must hold about the involved variables.
So, to use a constraint solver in Prolog, you simply use the predicates it provides, just as you would use any other Prolog predicate. In the example above, I am using the constraint (#=)/2, which is a predicate that is true iff its arguments evaluate to the same integer.
From the perspective of implementors, Prolog is a great implementation language for constraint solvers due to its built-in search and backtracking mechanisms. It also allows you to use the standardized Prolog syntax that many users are already familiar with, instead of having to devise yet another modeling language on top of your solver.
Thus, I would describe the relation as a natural symbiosis: It is natural to use constraint solvers in Prolog, and natural to implement them in Prolog.