Keele Research Repository

Modern high level programming languages have been designed with the intention of providing the means of expressing the solution to a problem in the most natural way possible. This thesis is concerned with the correctness of such solutions.
The reliability of programs is discussed and techniques for increasing the likelihood of producing a correct program are examined. In particular, the use of certain high level languages affording program control structures and data types that allow an easy and natural expression of a real problem is seen to be of paramount importance. It is argued that using such programming languages is severely hampered if, in the event of a program error, diagnostic information is not available in terms of the program structure and data.
This thesis is concerned with the provision of run-time diagnostic facilities. In particular,, the provision of such diagnostics for the user of data structures is seen as a currently neglected area.
The implementation of the programming language Pascal is described. Within this implementation, a unique interactive diagnostics system is built to allow the programmer complete diagnostic capabilities expressed in terms of the Pascal language. The main innovation provided is the ability to display the data structures built within a program in a manner in which the programmer views them. The reactions to this system are described and the extent to which it has achieved its aims discussed.