One obstacle to the implementation of modular extensions to programming languages lies in the problem of parsing extended languages. Specifically, the parse tables at the heart of traditional LALR(1) parsers are so monolithic and tightly constructed that, in the general case, it is impossible to extend them without regenerating them from the source grammar. Current extensible frameworks employ a variety of solutions, ranging from a full regeneration to using pluggable binary modules for each different extension.

Attribute grammar specification languages, like many domain-specific languages, offer significant advantages to their users, such as high-level declarative constructs and domain-specific analyses. Despite these advantages, attribute grammars are often not adopted to the degree that their proponents envision. One practical obstacle to their adoption is a perceived lack of both domain-specific and general purpose language features needed to address the many different aspects of a problem. Here we describe Silver, an extensible attribute grammar specification system, and show how it can be extended with general purpose features such as pattern matching and domain-specific features such as collection attributes and constructs for supporting data-flow analysis of imperative programs.

There is an increasing interest in domain-specific and extensible languages, and frameworks for developing extensions to them. One challenge is to develop tools that allow non-expert programmers to add an eclectic set of language extensions to a host language. In this paper we describe mechanisms for composing and analyzing syntactic specifications of a host language and extensions. These specifications consist of context-free grammars with each terminal symbol mapped to a regular expression, from which a slightly-modified LR parser and context-aware scanner are generated.

In model-based development, the software development effort is centered around a formal description of the proposed software system; a description that can be subjected to various types of analysis and code generation. Based on years of experience with model-based development and formal modeling we believe that the following conjectures describe fundamental obstacles to wide adoption of formal modeling and the potential for automation that comes with it; (1) no single modeling notation will suit all, or even most, modeling needs, (2) no analysis tool will fit all, or even most, analysis tasks, and (3) flexible and stable tools must be made available for realistic evaluations and technology transfer.

In this paper we describe a language extension that adds dimension analysis to Java. Dimension analysis can be used to check that values that represent physical measurements such as length and mass are not used inconsistently. What distinguishes this work from previous work that adds dimension analysis to programming languages is that here the extension is implemented as a composable language extension. This means that it can easily be combined with other extensions, possibly developed by other parties, to create an extended implementation of Java with new features that address concerns from several different domains.