Supported backend Prolog systems: ECLiPSe, SICStus Prolog, SWI-Prolog, and YAP.
Sets a constraint that is true iff the two terms are different.
Sets a set of constraints that are true iff all terms in a list are different.
Delays the execution of a goal until a variable is bound.
Goal with the goal delayed by
Variable. When no goals are frozen on
Goal is unified with true.