The author and his associates have been experimenting for the past several years with a programming language and documentation system called WEB. This paper presents WEB by example, and discusses why the new system appears to be an improvement over previous ones.

A query algebra is presented that expresses searches on structured text. In addition to traditional full-text boolean queries that search a pre-defined collection of documents, the algebra permits queries that harness document structure. The algebra manipulates arbitrary intervals of text, which are recognized in the text from implicit or explicit markup. The algebra has seven operators, which combine intervals to yield new ones: containing , not containing , contained in, not contained in, one of , both of , followed by . The ultimate result of a query is the set of intervals that satisfy it. An implementation framework is given based on four primitive access functions. Each access function finds the solution to a query nearest to a given position in the database. Recursive definitions for the seven operators are given in terms of these access functions. Search time is at worst proportional to the time required to solve the elementary terms in the query. Inverted indices yield search ...

In this paper we generalize the two level approach approach to hypertext (hypermedia) systems into stratified hypermedia structures. First we describe the overall architecture of such systems, including the fundamentals of the user interface. Thereafter, its various components are discussed. Special emphasis is paid to how the underlying information model is layered. Two layers are featured: the hyperbase and the hyperindex. A characterization calculus is presented for the characterization of structured elements. This calculus forms the basis of a logic-based approach in connection with the associated information processor (Disclosure Machine). The logic-based approach is considered as the most general approach to the retrieval process. In addition, this calculus is useful for quality assurance in hypermedia applications. Attention is also paid to spatial coherence for relevance judgements. 1 This work has been partially supported by the ESPRIT project APPED (2499). 1 1...

The MetaPost system implements a picture-drawing language very much like Knuth’s META-FONT except that it outputs PostScript commands instead of run-length-encoded bitmaps. MetaPost is a powerful language for producing figures for documents to be printed on PostScript printers. It provides easy access to all the features of PostScript and it includes facilities for integrating text and graphics. This document serves as an introductory user’s manual. It does not require knowledge of METAFONT or access to The METAFONTbook, but both are beneficial. An appendix explains

We have implemented an object-oriented user interface package, called InterViews, that supports the composition of a graphical user interface from a set of interactive objects. The base class for interactive objects, called an interactor, and base class for composite objects, called a scene, define a protocol for combining interactive behaviors. Subclasses of scene define common types of composition: a box tiles its components, a tray allows components to overlap or constrain each other's placement, a deck stacks its components so that only one is visible, a frame adds a border, and a viewport shows part of a component. Predefined components include menus, scrollers, buttons, and text editors. InterViews also includes classes for structured text and graphics. InterViews is written in C++ and runs on top of the X window system.

. Dynamic binding, which has always been associated with Lisp, is still semantically obscure to many. Although largely replaced by lexical scoping, not only does dynamic binding remain an interesting and expressive programming technique in specialised circumstances, but also it is a key notion in semantics. This paper presents a syntactic theory that enables the programmer to perform equational reasoning on programs using dynamic binding. The theory is proved to be sound and complete with respect to derivations allowed on programs in "dynamic-environment passing style". From this theory, we derive a sequential evaluation function in a context-rewriting system. Then, we exhibit the power and usefulness of dynamic binding in two different ways. First, we prove that dynamic binding adds expressiveness to a purely functional language. Second, we show that dynamic binding is an essential notion in semantics that can be used to define the semantics of exceptions. Afterwards, we further refin...

The Data Display Debugger (DDD) is a novel graphical user interface to GDB and DBX, the popular UNIX debuggers. Besides "usual" features such as viewing source texts and breakpoints, DDD provides a graphical data display, where data structures are displayed as graphs. A simple mouse click dereferences pointers or reveals structure contents. Complex data structures can be explored incrementally and interactively, using automatic layout if preferred. Each time the program stops, the data display reflects the current variable values. DDD has been designed to compete with well-known commercial debuggers; however, it is free software, protected by the GNU general public license. In this paper, we give a quick presentation of DDD and describe its architecture and basic functionality from a technical point of view.

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This paper describes the concept of language oriented programming which is a novel way of organising the development of a large software system, leading to a different structure for the finished product. The approach starts by developing a formally specified, domain-oriented, very high-level language which is designed to be well-suited to developing "this kind of program". The development process then splits into two independent stages: (1) Implement the system using this "middle level" language, and (2) Implement a compiler or translator or interpreter for the language, using existing technology. The approach is claimed to have advantages for domain analysis, rapid prototyping, maintenance, portability, user-enhanceable systems, reuse of development work, while also providing high development productivity. We give an example where the method has been used very successfully (in conjunction with rapid prototyping) in the development of a large software system: the FermaT reverse enginee...