Automatic Program Generation from Specifications Using Prolog

This paper describes an automatic program generator which creates PROLOG programs from input/output specifications. The generator takes as input descriptions of the input and output data types, a set of tests, a set of transformations and the input/output relation. Abstract data types are used as models for data. They are defined as sets of terms satisfying a system of equations. The tests, the transformations and the input/output relation are also specified by equations. The program generator creates a PROLOG program which takes as input a data item, iteml, of the input data type and outputs a data item, item2, of the output data type such that the input/output relation is satisfied by the pair iteml,item2. In building the program the generator uses only the tests and the transformations given as input. The program generator was writen in PROLOG. It was able to generate correct PROLOG programs for sorting lists with and without eliminating duplicate elements. The system contains specifications of the abstract data types natural number, boolean, list and array. The system can be used in two modes: in the first mode the user defines his/her own data types and in the second mode he/she uses the definitions that are already in the system library. A user interface is being constructed for the second class of users. The paper also presents several methods for validating the input/output specifications. Some of them were implemented in the system. Descriptions of the heuristics employed by the program synthesizer are also included. Finally, the paper compares this system with the approaches taken by other researchers in automatic program generation : Prywes, Manna and Dershowitz.