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Most current DFVPLs support flow control to facilitate experiments and complex problems. However, current approaches in DFVPLs still remain inefficient. We show that inadequacies in existing visual programming languages may be magnified in applications involving image analysis. These include a lack of efficient communication mechanisms and strong dependency on human involvement to customise properties. For instance, properties in one computational component can not be shared for other components. Moreover, conditional expressions used in control components hold data values that are unrelated with those computational components. Furthermore, since image processing libraries usua.lly only explicitly support pipeline processing, as exemplified by the widely used Insight Toolkit for Medical Image Segmentation and Registration (ITK), a looping algorithm would be difficult to implement without a feedback mechanism supported by the visual language itself. We propose a data-flow visual programming language that encompasses several novel control constructs and parameterised computational units. These components are facilitated by a novel hybrid data-flow model. We also present several conceptual models and design alternatives for control constructs. Several mechanisms and techniques are provided to enhance data propagation for these components. We demonstrate, in an environment that utilises ITK as the underlying processing engine, that the inadequacies in existing DFVPLs can be satisfactorily addressed through the visual components proposed in this thesis.

This thesis considers the design and implementation of a Declarative Debugger for Haskell. At its core is a tree which captures the logical dependencies between function calls in a given execution of the program being debugged (the debuggee). The debuggee is transformed into a new Haskell program which produces the tree in addition to its normal value. A bug is identified in the tree when a call returns the wrong result but all the calls it depends upon are correct.

Thesis (doctoral)--Technische Universiteit Delft, 2004. / Includes bibliographical references (p. 301-306).

Thesis (doctoral)--Technische Universiteit Delft, 2004. / Includes bibliographical references (p. 301-306).

Thesis (Ph. D.)--University of Cambridge, 1995. / Cover title. "April 1996." Includes bibliographical references.

Based on the author's D. Phil. Thesis (University of Oxford). / Includes bibliographical references. Available on-line.

Research into providing support for long term data in lazy functional programming systems is presented in this thesis. The motivation for this work has been to reap the benefits of integrating lazy functional programming languages and persistence. The benefits are: the programmer need not write code to support long term data since this is provided as part of the programming system; persistent data can be used in a type safe way since the programming language type system applies to data with the whole range of persistence; the benefits of lazy evaluation are extended to the full lifetime of a data value. Whilst data is reachable, any evaluation performed on the data persists. A data value changes monotonically from an unevaluated state towards a completely evaluated state over time. Interactive data intensive applications such as functional databases can be developed. These benefits are realised by the development of models for persistence in lazy functional programming systems. Two models are proposed which make persistence available to the functional programmer. The first, persistent modules, allows values named in modules to be stored in persistent storage for later reuse. The second model, stream persistence allows dynamic, interactive access to persistent storage. These models are supported by a system architecture which incorporates a persistent abstract machine, PCASE, integrated with a persistent object store. The resulting persistent lazy functional programming system, Staple, is used in prototyping and functional database modelling experiments.

The quest for speed and the need to solve ever more complex problems has led to the development of powerful computer systems, such as the Connection Machine. Concurrent processing promises a solution to the problem. COOL (Concurrent Object-Oriented Language) has been developed in order to provide the Connection Machine with a subset of C" which includes several concurrent constructs. The Connection Machine has an inherently parallel architecture which can be taken advantage of with software.

Action Semantics is a framework for defining the semantics of languages. It is intended to be accessible to a wider audience of Computer Scientists than traditional semantics frameworks (such as Denotational Semantics). There has been little work carried out to date on the techniques required to define object-oriented languages with Action Semantics. The work presented in this thesis examines four potential approaches to defining the Action Semantics of object-oriented languages. In order to illustrate the four approaches a simple language EIL (Example Inheritance Language) is given, and described using these four approaches. The language Smalltalk-80 has been selected for a case study of a practical application of one of the techniques described above. It is important to be able to relate Action Semantics definitions of object-oriented languages to similar definitions given in other frameworks. It is described how this can be achieved. An example is given for the Action Semantics and Denotational Semantics of Smalltalk. This thesis concludes that it is feasible to produce Action Semantics definitions of object-oriented languages.