LFMTP

This volume constitutes the proceedings of the Eighth International Workshop on Logical Frameworks and Meta-languages: Theory and Practice, LFMTP 2013. The LFMTP workshop series resulted from the amalgamation of the Logical Frameworks and Meta-languages (LFM) and the Mechanized Reasoning about Languages with Variable Binding (MERλIN) workshop series. Logical frameworks and meta-languages form a common substrate for representing, implementing, and reasoning about a wide variety of deductive systems of interest in logic and computer science.

LFMTP 2013 has a historical theme: "Twenty-five years of Logical Frameworks", based on the seminal publication describing the Edinburgh Logical Framework (LF), "A framework for defining logics", by Harper, Honsell and Plotkin in LICS 1987. (Both Harper and Honsell are invited speakers at LFMTP 2013.) Some of the ideas and techniques to uniformly represent and reason about formal systems go back well before 1987 (e.g., Church's representation of binding in the presentation of his Simple Theory of Types, but also contributions by many other people to many other aspects of the field). Nonetheless the years 1986-1990 were remarkably fruitful for modern notions of logical framework. The archaeological ancestor of LFMTP is the Workshop on General Logic held by the Edinburgh University Laboratory for Foundations of Computer Science in Feb. 1987. The Harper, Honsell and Plotkin paper on LF brought together the notions of higher order abstract syntax (HOAS) and judgments as types using dependent types. The best known current descendant of this LF work is the Twelf system, both theory and implementation, developed over many years by Frank Pfenning and his many collaborators. The paper by Wang and Nadathur in these proceedings continues this line of work. Work originally stemming from the LF paper has inspired much theoretical development over recent years; the paper by Cave and Pientka in this volume extends one of these lines of thinking.

Much else was going on in the field of logical frameworks in the years 1986-1990. Dale Miller and his collaborators showed that an intuitionistic fragment of Church's Simple Theory of Types also forms a powerful logical framework. (Miller is an invited speaker at LFMTP 2013.) Although the same HOAS approach is used here as in the Edinburgh LF/Twelf works, there are many important differences; e.g., higher order simple types vs. first order dependent types. The current descendants of this approach include the higher order logic programming language λProlog and the Abellasystem for reasoning about λProlog specifications.

Pure Type Systems (PTS), a very different kind of framework for a large class of type theories, was also developed in 1988-1990. Rather than a language for expressing formal systems, as the aforementioned frameworks, PTS is a single formal system that is parameterized in such a way that by different instantiations it captures many previously known type systems, and permits reasoning uniformly about interesting classes of type systems. The paper by van Doorn, Geuvers and Wiedijk in this volume furthers this approach.

The area of logical frameworks has continued to expand and inspire interesting technical developments. The remaining papers in these proceedings (Rasmussen and Filinski, Farooque, Graham-Lengrand and Mahboubi) only hint at how active and exciting the field is today.

LFMTP 2013 was held on September 23, 2013, in Boston, MA, USA, as a workshop associated with ICFP 2013, the 18th ACM SIGPLAN International Conference on Functional Programming. In addition to presentations of the contributed papers contained in this proceedings, the program included invited talks by Robert Harper (Carnegie Mellon University), Furio Honsell (Università di Udine) and Dale Miller (INRIA Saclay), together with a short paper presentation. The full program can be found at the web site for LFMTP 2013.

LFMTP is a referred workshop series. Each contributed paper was reviewed by three members of the program committee. Acceptance decisions were made by consensus, based on the reviews. Authors of accepted papers were given an opportunity to revise their manuscripts prior to their presentation to take cognizance of the reviews. The papers contained in these proceedings are the end result of this process.