Specifying Software Languages: Grammars, Projectional Editors, and Unconventional Approaches

We discuss several approaches for defining software languages, together with Integrated Development Environments for them. Theoretical foundation is grammar-based models: they can be used where proven correctness of specifications is required. From a practical point of view, we discuss how language specification can be made more accessible by focusing on language workbenches and projectional editing, and discuss how it can be formalized. We also give a brief overview of unconventional ideas to language definition, and outline three open problems connected to the approaches we discuss

Automating the teaching of artificial language using production systems

The work to be described here is an investigation into the means whereby the learning of programming languages may be made easier. The role of formal definitions of programming languages is studied and a system is described which utilises production systems as the basis for generating an environment in which students may test their understanding of programming languages. This system for automating the teaching of programming languages provides an experimental testbed for carrying out further investigations into programming behaviour

The van Wijngaarden grammars: A syntax primer with decidable restrictions

Expressiveness and decidability are two core aspects of programming languages that should be thoroughly known by those who use them; this includes knowledge of their metalanguages a.k.a. formal grammars. The van Wijngaarden grammars (WGs) are capable of generating all the languages in the Chomsky hierarchy and beyond; this makes them a relevant tool in the design of (more) expressive programming languages. But this expressiveness comes at a very high cost: The syntax of WGs is extremely complex and the decision problem for the generated languages is generally unsolvable. With this in mind, I provide here a short primer of the syntax of WGs, which includes syntactic restrictions that guarantee decidability for the corresponding generated languages

MediaWiki Grammar Recovery

The paper describes in detail the recovery effort of one of the official MediaWiki grammars. Over two hundred grammar transformation steps are reported and annotated, leading to delivery of a level 2 grammar, semi-automatically extracted from a community created semi-formal text using at least five different syntactic notations, several non-enforced naming conventions, multiple misspellings, obsolete parsing technology idiosyncrasies and other problems commonly encountered in grammars that were not engineered properly. Having a quality grammar will allow to test and validate it further, without alienating the community with a separately developed grammar.Comment: 47 page

Formal Specification Of Design Patterns: A Comparison Of Three Existing Approaches And Proposing Two-Level Grammars As A New Approach

Patterns are Object-Oriented reusable units. The principal idea behind patterns is to capture and reuse the abstractions that have been formed by expert programmers and designers to solve problems that occur in particular contexts. These abstractions capture the valuable experiences of experts in solving problems. Although patterns are currently being used successfully, there is no general agreement among the software community as to how patterns should be formalized or represented. Various formal specification schemes have been proposed to complement the natural language description of patterns in order to alleviate the ambiguities inherent in the natural language description by rigorously reasoning about the structural and behavioral aspects of patterns. Existing formal specification languages of design patterns have generally failed to provide a standard definition, specification, or representation for patterns because there is no general agreement as to how patterns should be formalized. Also, each formal specification is generally based on a different mathematical formalism and when pattern users want to understand a pattern, first they have to understand the respective mathematical formalism. In addition to comparing three existing formal specification schemes, the main objective of this research work was to lay the foundation for developing a formal specification scheme that could be understandable without having to delve into the details of the underlying formalism. This research work attempted to capture and represent the structural aspects of design patterns since capturing the behavioral aspects of design patterns is a semantic issue and is beyond the scope of this work. Two-Level Grammar (TLG) was used to capture and represent the structural aspects of design patterns. This study was conducted using the GoF design patterns [Gamma et al. 1995]. It has already been demonstrated that TLGs have the capability to represent the building blocks of object-oriented software systems. The primary advantage of TLGs in defining design patterns is that specifications written in TLGs are understandable due to their natural-language-like vocabulary [Edupuganty 1987] [Lee 2003] [Maluszynski 1984]. The TLG representation of the observer pattern was developed to gauge the feasibility of the proposed pattern representation scheme. TLGs could help pattern users understand the formalized version of patterns more readily compared to other formal specification methods that are difficult to understand due to their arcane mathematical notations.Computer Science Departmen