Roman Knoell, Mira Mezini. pi: a pattern language. In Shail Arora, Gary T. Leavens, editors, Proceedings of the 24th Annual ACM SIGPLAN Conference on Object-Oriented Programming, Systems, Languages, and Applications, OOPSLA 2009, October 25-29, 2009, Orlando, Florida, USA. pages 503-522, ACM, 2009. [doi]
Current programming languages and techniques realize many features which allow their users to extend these languages on a semantic basis: classes, functions, interfaces, aspects and other entities can be defined. However, there is a lack of modern programming languages which are both semantically and syntactically extensible from within the language itself, i.e., with no additional tool or meta-language. In this paper we present π as an approach that aims to overcome this lack. π provides an abstraction mechanism based on parameterized symbols which is capable of semantically and syntactically unifying programming concepts like variables, control-structures, procedures and functions into one concept: the pattern. We have evaluated the abstraction potential and the syntactic extensibility of π by successfully creating patterns for the aforementioned programming concepts. π could serve as a tool for designing new experimental languages and might generally influence the view we have on current programming concepts.