Automatic Programming From Data Types Decomposition Patterns

A running system is presented which provides powerful support to the user while designing programs . This system automatically constructs program sche-mas by decomposition of the datas involved in the specification. Datas are specified within a knowledge base as data types having associated decomposition patterns. The user may combine different data-decomposition strategies with any of its decomposition patterns. So it is possible to build several program schemas for the same problem. Once a program schema is built the user can instantiate or adapt it by hand. He can also apply the system repetitively until he obtains primitive problems which can be solved directly. I INTRODUCTION In the attempt to automatically construct a program from its specification two main approaches have been proposed.-The first method acts in a formal framework and uses a deductive mecanism to solve the problem. The desired program can be obtained by proving a theorem in a constructive way [M.W 80], or by applying the Knuth-Bendix completion procedure to a rewrite system [ DER 82] .-The second method is based on a large, amount of knowledge that one can have about some aspects of programming. This knowledge base contains a lot of rules and facts which allow gradual refinement and transformation of a specification into an efficient program [BAR 79] [B.O.R 81]. However as previously noticed [ BAR 83] , none of these approaches is really satisfying. The first one can't avoid the combinatorial explosion inherent to this kind of mecanism. The second one, lacking of relevant rules for algorithm creation can only synthesize programs from algorithmic specifications. A third method can be tried in partially automating the software development and providing a powerful aid to the programmer. Such an example is the Pro-grammer's Apprentice [ WAT 82] designed to be midway between an improved programming methodology and an automatic synthesis system. The system presented in this paper, called the Program Builder (PB), belongs to this third method. It relies heavily on a top-down and modular approach and constructs automatically a program schema by decomposing the initial problem with respect to the data structures involved in its specification. This program schema introduces new sub-problems and eventually some guards which must be verified to validate these sub-problems. Decomposition is done by processing structured data objects independantly of the semantics of the problem : so in some cases the program schema may be irrelevant. In the more favourable cases …