Fruit is a new graphical user interface library for Haskell based on a formal model of user interfaces. The model identifies signals (continuous time-varying values) and signal transformers (pure functions mapping signals to signals) as core abstractions, and defines GUIs compositionally as signal transformers. In this paper, we describe why we think a formal denotational model of user interfaces is useful, present our model and prototype library implementation, and show some example programs that demonstrate novel features of our library.

Based on our experience with modelling and verifying microarchitectural designs within Haskell, this paper examines our use of Haskell as host for an embedded language. In particular, we highlight our use of Haskell's lazy lists, type classes, lazy state monad, and unsafePerformIO, and point to several areas where Haskell could be improved in the future. We end with an example of a benefit gained by bringing the functional perspective to microarchitectural modelling.

. Functional languages are particularly well-suited to the implementation of interpreters for domain-specific embedded languages (DSELs). We describe an implemented technique for producing optimizing compilers for DSELs, based on Kamin's idea of DSELs for program generation. The technique uses a data type of syntax for basic types, a set of smart constructors that perform rewriting over those types, some code motion transformations, and a back-end code generator. Domain-specific optimization results from chains of rewrites on basic types. New DSELs are defined directly in terms of the basic syntactic types, plus host language functions and tuples. This definition style makes compilers easy to write and, in fact, almost identical to the simplest embedded interpreters. We illustrate this technique with a language Pan for the computationally intensive domain of image synthesis and manipulation. 1 1 Introduction The "embedded" approach has proved an excellent technique for ...

Functional Reactive Programming (FRP) is a declarative programming model for constructing interactive applications based on a continuous model of time. FRP programs are described in terms of behaviors (continuous, timevarying, reactive values), and events (conditions that occur at discrete points in time). This paper presents Frappe, an implementation of FRP in the Java progamming language. The primary contribution of Frappe is its integration of the FRP event/behavior model with the Java Beans event/property model. At the interface level, any Java Beans component may be used as a source or sink for the FRP event and behavior combinators. This provides a mechanism for extending Frappe with new kinds of I/O connections and allows FRP to be used as a high-level declarative model for composing applications from Java Beans components. At the implementation level, the Java Beans event model is used internally by Frappe to propagate FRP events and changes to FRP behaviors. This allows Frappe applications to be packaged as Java Beans components for use in other applications, and yields an implementation of FRP well-suited to the requirements of event-driven applications (such as graphical user interfaces). 1

Abstract. In this paper, we demonstrate how Functional Reactive Programming (FRP), a framework for the description of interactive systems, can be extended to encompass parallel systems. FRP is based on Haskell, a purely functional programming language, and incorporates the concepts of time variation and reactivity. Parallel FRP serves as a declarative system model that may be transformed into a parallel implementation using the standard program transformation techniques of functional programming. The semantics of parallel FRP include non-determinism, enhancing opportunities to introduce parallelism. We demonstrate a variety of program transformations based on parallel FRP and show how a FRP model may be transformed into explicitly parallel code. Parallel FRP is implemented using the Linda programming system to handle the underlying parallelism. As an example of parallel FRP, we show how a specification for a web-based online auctioning system can be transformed into a parallel implementation. 1

A great challenge in information visualization today is to provide models and software that effectively integrate the graphics content of scenes with domain-specific knowledge so that the users can effectively query, interpret, personalize and manipulate the visualized information [1]. Moreover, it is important that the intelligent visualization applications are interoperable in the semantic web environment and thus, require that the models and software supporting them integrate state-of-the-art international standards for knowledge representation, graphics and multimedia. In this paper, we present a model, a methodology and a software framework for the semantic web (Intelligent 3D Visualization Platform -- I3DVP) for the development of interoperable intelligent visualization applications that support the coupling of graphics and virtual reality scenes with domain knowledge of different domains. The graphics content and the semantics of the scenes are married into a consistent and cohesive ontological model while at the same time knowledge -based techniques for the querying, manipulation, and semantic personalization of the scenes are introduced. We also provide methods for knowledge driven information visualization and visualization -aided decision making based on inference by reasoning.

Experiences are presented from a new case study of embedding domain-specific languages in the lazy functional language Haskell. The domain languages come from the Odin software build system. Thus, in contrast to most previous embedding projects, a design and implementation of the domain languages existed when the project began. Consequently, the design could not be varied to suit the target language and it was possible to evaluate the success or otherwise of the embedding process in more detail than if the languages were designed from scratch. Experiences were mostly positive. The embedded implementation is significantly smaller than its Odin equivalent. Many benefits are obtained from having the full power of an expressive programming language available to the domain programmer. The project also demonstrates in a practical software engineering setting the utility of modern functional programming techniques such as lazy evaluation and monads for structuring programs. On the down side, the efficiency of the embedded version compares unfavourably to the original system.

The creation of engaging, interactive virtual environments is a difficult task, but one that can be eased with the development of better software support. This paper proposes that a better understanding of the problem of building Dynamic, Interactive Virtual Environments must be developed. Equipped with an understanding of the design space of Dynamics, Dynamic Interaction, and Interactive Dynamics, the requirements for such a support system can be established. Finally, a system that supports the development of such environments is briefly presented, Functional Reactive Virtual Reality.

In the paper a design and implementation of Simple Object Description Language SODL for automatic interface creation are presented. First, problem domain -- developing network applications and reasons for developing new domain-specific language are described. Since the cross network method calls slow down performance of our applications the solution was Tier to Tier Object Transport (TTOT). However, with this approach the network application development time has been increased. To enhance our productivity a new domain-specific SODL language has been designed. Syntax and semantics of SODL language are formally defined in an incremental way by special kind of attribute grammars that allows extensions and modifications in an easy way. From formal specifications SODL compiler is automatically generated using compiler/interpreter generator tool LISA. Finally, the benefits of our approach have been discussed. 1.

Abstract. Domain-specific languages (DSLs) have been proposed as a solution to ease the development of programs within a program family. Sometimes, however, experience with the use of a DSL reveals the presence of subfamilies within the family targeted by the language. We are then faced with the question of how to capture these subfamilies in DSL abstractions. A solution should retain features of the original DSL to leverage existing expertise and support tools. The Bossa DSL is a language targeted towards the development of kernel process scheduling policies. We have encountered the issue of program subfamilies in using this language to implement an encyclopedic, multi-OS library of scheduling policies. In this paper, we propose that introducing certain kinds of modularity into the language can furnish abstractions appropriate for implementing scheduling policy subfamilies. We present the design of our modular language, Bossa Nova, and assess the language quantitatively and qualitatively. 1