Programming Language Issues Research Articles

Program equivalence in linear contexts

Program equivalence in linear contexts, where programs are used or executed exactly once, is an important issue in programming languages. However, existing techniques like those based on bisimulations and logical relations only target at contextual equivalence in the usual (non-linear) functional languages, and fail in capturing non-trivial equivalent programs in linear contexts, particularly when non-determinism is present.We propose the notion of linear contextual equivalence to formally characterize such program equivalence, as well as a novel and general approach to studying it in higher-order languages, based on labeled transition systems specifically designed for functional languages. We show that linear contextual equivalence indeed coincides with trace equivalence. We illustrate our technique in both deterministic (a linear version of PCF) and non-deterministic (linear PCF in Moggi's framework) functional languages.

Highlighting programming language issues using mixed language programming nn Maple and C

Three examples using mixed language programming in Maple and C are provided for the express purpose of highlighting, in a practical way, various issues normally discussed in a traditional programming languages class only as theoretical concepts. The three examples highlight concepts in parameter passing techniques, storage order choices, native machine types and sizes, and the handling of single and multi-dimensional arrays when dealing with legacy code.

VIPR and the Visual Programming Challenge

The Visual Programming Challenge (VPC) provides a framework for exploring visual programming language issues in a quasi-real-time environment and for comparing competing languages. VIPR is an attempt to bring the traditional strengths of textual imperative languages to a visual programming language. It leverages these strengths to make use of well-understood design and abstraction methodologies while providing additional visual features, such as explicit representations, contextual information, and execution animation. VIPR uses these strengths and features to address the quasi-real-time problem posed by the VPC, whose requirements include interaction with the low-level vehicle manipulation code, map exploration and display, as well as additional requirements such as flexibility of solution and performance demands. Our solution does not directly address pedagogical issues or the value of VIPR's simple graphical semantics. It did point out weaknesses with VIPR's approach to solving the scalability problem in visual programming languages.

Programming language issues for the 1980's

At the SIGPLAN '83 conference, a panel discussion was held to discuss what the important programming language issues might be in the 1980's. This paper is an edited transcript of the discussion.I want to thank John White, General Chairman for the conference, who suggested that we have the panel and Richard Probst and Tim Learmont from U.C. Berkeley who recorded and transcribed the discussion. In the transcript below we have identified the speakers where possible. We apologize to those members of the audience whose comments are included below but who are not identified because we did not know their name.

Medical computing in the 1980s. Operating system and programming language issues.

Operating systems and programming languages differ widely in their suitability for particular applications. The diversity of medical computing needs demands a diversity of solutions. Compounding this diversity if the decentralization caused by evolution of local computing systems for local needs. Relevant current trends in computing include increased emphasis on decentralization, growing capabilities for interconnection of diverse systems, and development of common data base and file server capabilities. In addition, standardization and hardware in dependence of operating systems, as well as programming languages and development of programmerless systems, continue to widen application opportunities.