Source : Free On-Line Dictionary of Computing

Qu-Prolog
     
        An extension of {Prolog} which performs {meta-level
        computation}s over {object language}s, such as {predicate
        calculi} and {lambda-calculi}, which have object-level
        variables, and {quantifier}s that create local {scope}s for
        those variables. Qu-Prolog is well suited as an implementation
        language for {theorem prover}s and support notations typically
        found in texts on mathematics and logic.