Papers by Andre van Delft
The Scriptive Programming Language
Over the last years a vast number of parallel languages have been developed. A large part of thes... more Over the last years a vast number of parallel languages have been developed. A large part of these are not available on ‘normal’ computers, or they do not cooperate easily with other languages. This paper describes Scriptic, a parallel language that extends widely used sequential languages (C, C++). Scriptic offers great expressiveness by incorporating many concepts from process theory dealing with concurrency and communication. Its availability on normal computers allows many software developers to experiment with parallel programming.
Recidive, werkstraf en gevangenisstraf: een kritische bespreking
Tijdschrift voor criminologie, 2013
The dataflow programming paradigm addresses how data flows inside programs. Program components, t... more The dataflow programming paradigm addresses how data flows inside programs. Program components, that are often concurrently active, send data to one another; this eases software composition. Mainstream programming languages do not support the paradigm well because of their deterministic and sequential nature. A language that focuses on concurrency is better suited to incorporate concepts from the dataflow paradigm. SubScript is an extension to the Scala programming language with constructs from the Algebra of Communicating Processes, targeted at event-driven and concurrent programming. Like ACP, SubScript focuses on program behavior; support for data was through local variables and parameters. However, the ACP background enabled SubScript to deal with the challenges of the dataflow paradigm. This is achieved through several new features. 1. A process may have a result value, like a method 2. A process result value may be passed on to another process that starts subsequently. This helps getting rid of variables, e.g., in GUI controller specifications. 3. Output actions from a process may be piped to a parallel process, yielding a similar expressiveness as pipes in Unix command shell language. 4. Actors written in Scala often need to keep track of a state, and their program text poorly expresses the conceptual control flow. When such actors are written in SubScript, incoming data may be treated as events that may appear anywhere in the specification, just like in SubScript GUI specifications.
Software - Practice and Experience, Jun 1, 1999
We present an extension to the Java language with support for physical dimensions and units of me... more We present an extension to the Java language with support for physical dimensions and units of measurement. This should reduce programming errors in scientific and technological areas. We discuss various aspects of dimensions and units, and then design principles for support in programming languages. An overview of earlier work shows that some language extensions focused on units, whereas we argue that dimensions are a better starting point; units can then simply be treated as constants. Then we present the Java extension, and show how to define and use dimensions and units. The communication between the program and the outer world gets special attention. The programmer can still make dimensional errors there, but we claim the risk is reduced. It has been simple to build support for this extension into an existing Java compiler. We outline the applied technique.
arXiv (Cornell University), Apr 14, 2015
This paper lists some new directions for research related to the Algebra of Communicating Process... more This paper lists some new directions for research related to the Algebra of Communicating Processes (ACP). Most of these directions have been inspired by work on SubScript, an ACP based extension to the programming language Scala. SubScript applies several new ideas that build on ACP, but currently these lack formal treatment. Some of these new ideas are rather fundamental. E.g. it appears that the theory of ACP may well apply to structures of any kind of items, rather than to just processes. The aim of this list is to raise awareness of the research community about these new ideas; this could help both the research area and the programming language SubScript.
The Scriptic Programming Language
Springer eBooks, 1991
Programming languages: an interpreter-based approach
Information & Software Technology, 1992
Computers & graphics, 1987
The advent of increasingly powerful graphics boards for personal computers will soon allow quite ... more The advent of increasingly powerful graphics boards for personal computers will soon allow quite advanced molecular graphics applications on inexpensive personal computer configurations. This paper describes an interactive molecular data display program, called WAALSURF, implemented on two different personal computers, IBM's PC-AT equipped with a Professional Graphics Adapter and Commodore's Amiga. These programs allow the inspection of data bases containing data of molecules with some thousand atoms each. The molecular data can be used to generate a range of representations from skeleton, ball-and-stick to space filled Van der Waals surfaces. To foster 3D perception coloring, perspective and lighting depth cues are included, with stereo images as an option. A versatile user interface is provided, allowing the operator to manipulate objects as well as display parameters. Under interactive control the user may rotate molecules in static or animation mode, label sections, strip outer layers and dock molecules while changing the color and the number of atoms displayed. A logging facility is provided to resume a new session where the previous one left off.
This paper lists some new directions for research related to the Algebra of Communicating Process... more This paper lists some new directions for research related to the Algebra of Communicating Processes (ACP). Most of these directions have been inspired by work on SubScript, an ACP based extension to the programming language Scala. SubScript applies several new ideas that build on ACP, but currently these lack formal treatment. Some of these new ideas are rather fundamental. E.g. it appears that the theory of ACP may well apply to structures of any kind of items, rather than to just processes. The aim of this list is to raise awareness of the research community about these new ideas; this could help both the research area and the programming language SubScript.
Softw. Pract. Exp., 1999
double*Speed divide (double*Length, double*Time); The original Java language specification define... more double*Speed divide (double*Length, double*Time); The original Java language specification defines: The signature of a method consists of the name of the method and the number and types of formal parameters to the method.. This definition does not change; hence a method signature does not contain dimension specifiers of the formal parameters. Instead the dimension specifiers constitute a rather independent dimension signature for the method. An unchanged rule from the Java language specification is: A class may not declare two methods with the same signature, or a compile-time error occurs. So adding another divide method with different dimensions would cause a function already defined error: abstract double*Acceleration divide(double*Speed, double*Time);//errordouble*Acceleration divide(double*Speed, double*Time);//error Instance methods may override others in superclasses and interfaces that have equal method signatures. A notable restriction is that the return types are equal. An...
Proceedings of the 4th Workshop on Scala - SCALA '13, 2013
The dataflow programming paradigm addresses how data flows inside programs. Program components, t... more The dataflow programming paradigm addresses how data flows inside programs. Program components, that are often concurrently active, send data to one another; this eases software composition. Mainstream programming languages do not support the paradigm well because of their deterministic and sequential nature. A language that focuses on concurrency is better suited to incorporate concepts from the dataflow paradigm. SubScript is an extension to the Scala programming language with constructs from the Algebra of Communicating Processes, targeted at event-driven and concurrent programming. Like ACP, SubScript focuses on program behavior; support for data was through local variables and parameters. However, the ACP background enabled SubScript to deal with the challenges of the dataflow paradigm. This is achieved through several new features. 1. A process may have a result value, like a method 2. A process result value may be passed on to another process that starts subsequently. This helps getting rid of variables, e.g., in GUI controller specifications. 3. Output actions from a process may be piped to a parallel process, yielding a similar expressiveness as pipes in Unix command shell language. 4. Actors written in Scala often need to keep track of a state, and their program text poorly expresses the conceptual control flow. When such actors are written in SubScript, incoming data may be treated as events that may appear anywhere in the specification, just like in SubScript GUI specifications.
Declarative Programming with Algebra
Lecture Notes in Computer Science, 2016
Recidive, werkstraf en gevangenisstraf: een kritische bespreking
Tijdschrift Voor Criminologie, 2013
Lecture Notes in Computer Science, 1991
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Papers by Andre van Delft