ARL and PR2, reversible languages

This paper is devoted to the description of the languages ARL and PR2. ARL can be viewed as a cross-fertilization of term rewriting systems and functional languages. The key concept in the language is reversibility, which means informally, that under certain circumstances, we can reconstruct the question from the answer. PR2 is an extension to ARL to make it more suitable for our domain of application: the translation between programming languages. Keywords: reversibility, analysis, generation, controlled continued analysis, pairing, rules, strategy, driver, matching, interlingua. Acknowledgements No-one pulls it off without the help of others, so I guess that includes me: first I'd like to thank the ones, with whom I talked 'professionally': Paul Jansen for our discussion over the phone of 4 2 and its relation with PR2, Gert-Jan Kamsteeg for our discussion on the matching of patterns and his suggestion to use empty rules in concatenations, Henk Goeman for his help with the book of ..