A Persistent Graphics Facility for the ICL Perq

The facilities of the PS-algol programming language are described in this paper to show how they may be used to provide an integrated programming support environment. The persistent store mechanism and the secure transaction facilities provide the basic environment in which an integrated system may be implemented. In particular the paper makes use of the data type picture of PS-algol to show how such an environment may be built for a graphics system ideal for use with a medium range computer workstation. An implementation of a picture editor on the ICL PERQ workstation is described to show the utility of the system

A Persistent Graphics Facility for the ICL Perq

The facilities of the PS-algol programming language are described in this paper to show how they may be used to provide an integrated programming support environment. The persistent store mechanism and the secure transaction facilities provide the basic environment in which an integrated system may be implemented. In particular the paper makes use of the data type picture of PS-algol to show how such an environment may be built for a graphics system ideal for use with a medium range computer workstation. An implementation of a picture editor on the ICL PERQ workstation is described to show the utility of the system

On the Utilisation of Persistent Programming Environments

There is a growing gap between the supply and demand of good quality software, which is primarily due to the difficulty of the programming task and the poor level of support for programmers. Programming is carried out using software tools which do not match very well either real world understanding of a problem or even the other tools which need to be used. In every phase of software production, the programmer must master new tools which function in a different way from each other. The Persistent Programming Paradigm attempts to reduce these problems by providing a programming environment which gives consistent methods of accessing program values of various kinds. Long-term and short-term data are treated in the same way. Numbers, text, graphical values and even program objects are all referred to in the same consistent way. Languages which support persistence provide considerable power within a simple environment, so that programmers can perform most if not all parts of the programming task in a coherent and uniform manner. This thesis tests the hypothesis that programmers do in fact derive some benefit from this - the simplification of the program and faster implementation of complex programs. The persistent language PS-algol is introduced and used to build: user-interface and compiler tools; a database application; some data modelling tools, both relational and semantic; a rapid prototyping system; an object-oriented language; and software support systems. In doing so, the thesis demonstrates the breadth of work which can be achieved using a Persistent Programming Language, and the ease with which these various projects can be implemented. Further, the thesis derives the beginnings of a methodology for using such a language and analyses how PS-algol could be improved. In doing so, the work aims to put the Persistent Programming Paradigm on a firm basis following significant use and experimentation

On the construction of persistent programming environments

This thesis presents research into the construction of persistent programming systems. Much of the thesis is concerned with the design and implementation of persistent programming languages, in particular PS-algol and Napier. Both languages support machine independent vector and raster graphics data types. Napier provides an environment mechanism that enables the incremental construction and binding of programs. Napier has a powerful type system featuring parametric polymorphism and abstract data types. The machine supporting Napier, the Persistent Abstract Machine, is investigated. The machine supports an efficient implementation of parametric polymorphism and abstract data types. The Persistent Abstract Machine has a layered architecture in which permits experimentation into language implementation and store design. The construction of compilers in a persistent environment is explored. A flexible compiler architecture is developed. With it, a family of compilers may be constructed at relatively little cost. One such compiler is the callable compiler; this is a first class data object in the persistent environment. The uses of such a compiler are explored, in particular in the construction of an object browser. The persistent object browser introduces a new software architecture that permits adaptive programs to be constructed incrementally. This is achieved by writing, compiling and linking new procedures into an executing program. The architecture has been successfully applied to the construction of adaptive databases and bootstrap compilers