Absys was an early declarative programming language from the University of Aberdeen. It anticipated a number of features of Prolog such as negation as failure, aggregation operators, the central role of backtracking and constraint solving. Absys was the first implementation of a logic programming language. Absys was an early declarative programming language from the University of Aberdeen. It anticipated a number of features of Prolog such as negation as failure, aggregation operators, the central role of backtracking and constraint solving. Absys was the first implementation of a logic programming language. The name Absys was chosen as an abbreviation for Aberdeen System.