We present a compiled implementation of Prolog that uses the abstract memory MALI for representing the execution state. Prolog is a logic programming language allowing a more general clause form than Standard Prolog 's (namely hereditary Harrop formulas instead of Horn formulas) and using simply typed -terms as a term domain instead of first order terms. The augmented clause form causes the program (a set of clauses) and the signature (a set of constants) to be changeable in a very disciplined way. The new term domain has a semi-decidable and infinitary unification theory, and it introduces the need for a fi-reduction operation at run-time. MALI is an abstract memory that is suitable for storing the search-state of depth-first search processes. Its main feature is its efficient memory management. We have used an original Prolog-to-C translation along which predicates are transformed into functions operating on continuations for handling failure and success in unifications, and change...

A logic grammar formalism called DCG (Definite Clause Grammars), which has proved to be useful, is part of most Prolog implementations. We develop two new logic grammar formalisms called DCG' and HHG (higher-order Hereditary Harrop Grammars) that can be used in Prolog implementations. The relations between DCG, DCG', and HHG, and Prolog and Prolog can be illustrated by the following diagram: DCG --3--? DCG' --------4---------? LambdaHHG --- " --- 1 --- "3 --- 4 --- " --- v v v Prolog -------------------2---------? LambdaProlog 1. The language Prolog, the DCG formalism, and the translation of DCG into Prolog by Prolog are classical. 2. The evolution from Prolog to Prolog is due to Miller and the advantage of using Prolog for doing natural language analysis is shown by Pereira, and Pareschi and Miller. 3. We propose a strongly typed variant of DCG (DCG' in the diagram) for its translation into Prolog by Prolog. It is a first stage towards a more elaborate formalism. 4. A formal...