23rd International Symposium on
Principles and Practice of Declarative Programming

PPDP 2021

6-8 September 2021, Tallinn, Estonia

Collocated with LOPSTR 2021


Overview of PPDP 2021

The PPDP 2021 symposium brings together researchers from the declarative programming communities, including those working in the functional, logic, answer-set, and constraint handling programming paradigms. The goal is to stimulate research in the use of logical formalisms and methods for analyzing, performing, specifying, and reasoning about computations, including mechanisms for concurrency, security, static analysis, and verification.


Submissions are invited on all topics related to declarative programming, from principles to practice, from foundations to applications. Topics of interest include, but are not limited to

  • Language Design: domain-specific languages; interoperability; concurrency, parallelism and distribution; modules; functional languages; reactive languages; languages with objects; languages for quantum computing; languages inspired by biological and chemical computation; metaprogramming.

  • Declarative languages in artificial intelligence: logic programming; database languages; knowledge representation languages; probabilistic languages; differentiable languages.

  • Implementations: abstract machines; interpreters; compilation; compile-time and run-time optimization; memory management.

  • Foundations: types; logical frameworks; monads and effects; semantics.

  • Analysis and Transformation: partial evaluation; abstract interpretation; control flow; data flow; information flow; termination analysis; resource analysis; type inference and type checking; verification; validation; debugging; testing.

  • Tools and Applications: programming and proof environments; verification tools; case studies in proof assistants or interactive theorem provers; certification; novel applications of declarative programming inside and outside of CS; declarative programming pearls; practical experience reports and industrial application; education.

The PC chair will be happy to advise on the appropriateness of a topic.

PPDP 2021 will be held in Tallinn, Estonia. Previous symposia were held at Bologna (Italy), Porto (Portugal), Frankfurt am Main (Germany), Namur (Belgium), Edinburgh (UK), Siena (Italy), Canterbury (UK), Madrid (Spain), Leuven (Belgium), Odense (Denmark), Hagenberg (Austria), Coimbra (Portugal), Valencia (Spain), Wroclaw (Poland), Venice (Italy), Lisboa (Portugal), Verona (Italy), Uppsala (Sweden), Pittsburgh (USA), Florence (Italy), Montréal (Canada), and Paris (France).

Invited Speakers

  • Marco Gaboardi, Boston University (PPDP invited speaker)
    Programming Languages Techniques for Controlling Generalization Errors in Adaptive Data Analysis

  • Harald Søndergaard, University of Melbourne (joint PPDP-LOPSTR invited speaker)
    String abstract domains and their combination

  • Stephen Wolfram, Wolfram Research (joint PPDP-LOPSTR invited speaker)
    The Computational Structure of the Universe and of Programs

  • Bernardo Toninho, Luís Caires, and Frank Pfenning. (10 Year Most Influential Paper Award, PPDP 2011).
    A Decade of Dependent Session Types


Accepted Papers

  • Kwanghoon Choi, James Cheney, Sam Lindley and Bob Reynders.
    A Typed Slicing Compilation of the Polymorphic RPC Calculus
  • Ieva Daukantas, Alessandro Bruni and Carsten Schürmann.
    Trimming Data Sets: a Verified Algorithm for Robust Mean Estimation
  • Dariusz Biernacki, Mateusz Pyzik and Filip Sieczkowski.
    Reflecting Stacked Continuations in a Fine-Grained Direct-Style Reduction Theory
  • Jayanth Krishnamurthy and Manuel Serrano.
    Causality Error Tracing in HipHop.js
  • Ugo De'Liguoro and Riccardo Treglia.
    Intersection types for a lambda-calculus with global store
  • Gaspard Férey and Jean-Pierre Jouannaud.
    Confluence in Non-Left-Linear Untyped Higher-Order Rewrite Theories
  • Horatiu Cirstea, Pierre Lermusiaux and Pierre-Etienne Moreau.
    Static analysis of pattern-free properties
  • Jan Dageförde, Hendrik Winkelmann and Herbert Kuchen.
    Free Objects in Constraint-logic Object-oriented Programming
  • Joosep Jääger and Alisa Pankova.
    PrivaLog: a Privacy-aware Logic Programming Language
  • Małgorzata Biernacka, Witold Charatonik and Tomasz Drab.
    A Derived Reasonable Abstract Machine for Strong Call by Value
  • Alen Arslanagic, Anda-Amelia Palamariuc and Jorge A. Pérez.
    Minimal session types for the pi-calculus
  • Serdar Erbatur, Ulrich Schöpp and Chuangjie Xu.
    Type-based Enforcement of Infinitary Trace Properties for Java
  • Rachid Echahed, Mnacho Echenim, Mehdi Mhalla and Nicolas Peltier.
    A Superposition-Based Calculus for Diagrammatic Reasoning
  • Mathias Jakobsen, Alice Ravier and Ornela Dardha.
    Papaya: Global Typestate Analysis of Aliased Objects
  • Jonas Böhm, Michael Hanus and Finn Teegen.
    From Non-determinism to Goroutines: A Fair Implementation of Curry in Go
  • David Zhao, Pavle Subotic, Mukund Raghothaman and Bernhard Scholz.
    Towards Elastic Incrementalization for Datalog
  • Abhishek De, Luc Pellisier and Alexis Saurin.
    Canonical proof-objects for coinductive programming: infinets with infinitely many cuts
  • Luís Carvalho and João Costa Seco.
    Deep Semantic Versioning for Evolution and Variability
  • Paul Rowe, John Ramsdell and Ian Kretz.
    Automated Trust Analysis of Copland Specifications for Layered Attestation
  • William Harrison, Chris Hathhorn and Gerard Allwein.
    A Mechanized Semantic Metalanguage for High Level Synthesis

Program Committee

Steering Committee Chair

James Cheney    Edinburgh University

Important Dates

  • 18.05.2021 AoE: title and abstract submission (extended)
  • 25.05.2021 AoE: paper submission (extended)
  • 29.06.2021: rebuttal period (48 hours)
  • 09.07.2021: notification
  • 23.07.2021: final papers
  • 06.09.2021: conference starts

Call for Papers

The Call for Papers is available in a a plain text and via EasyChair.

Submission Categories & Guidelines

Submission site: easychair.org/conferences/?conf=ppdp2021

Submission Categories

Submissions can be made in three categories: regular Research Papers, System Descriptions, and Experience Reports.

Submissions of Research Papers must present original research which is unpublished and not submitted elsewhere. They must not exceed 12 pages ACM style 2-column (including figures, but excluding bibliography). Work that already appeared in unpublished or informally published workshop proceedings may be submitted (please contact the PC chair in case of questions). Research papers will be judged on originality, significance, correctness, clarity, and readability.

Submission of System Descriptions must describe a working system whose description has not been published or submitted elsewhere. They must not exceed 10 pages and should contain a link to a working system. System Descriptions must be marked as such at the time of submission and will be judged on originality, significance, usefulness, clarity, and readability.

Submissions of Experience Reports are meant to help create a body of published, refereed, citable evidence where declarative programming such as functional, logic, answer-set, constraint programming, etc., is used in practice. They must not exceed 5 pages including references. Experience Reports must be marked as such at the time of submission and need not report original research results. They will be judged on significance, usefulness, clarity, and readability.

Possible topics for an Experience Report include, but are not limited to:

  • insights gained from real-world projects using declarative programming
  • comparison of declarative programming with conventional programming in the context of an industrial project or a university curriculum
  • curricular issues encountered when using declarative programming in education
  • real-world constraints that created special challenges for an implementation of a declarative language or for declarative programming in general
  • novel use of declarative programming in the classroom
  • programming pearl that illustrates a nifty new data structure or programming technique.

Supplementary material may be provided via a link to an extended version of the submission (recommended), or in a clearly marked appendix beyond the above-mentioned page limits. Reviewers are not required to study extended versions or any material beyond the respective page limit. Material beyond the page limit will not be included in the final published version.

Format of a submission

For each paper category, you must use the most recent version of the "Current ACM Master Template" which is available at https://www.acm.org/publications/proceedings-template. The most recent version at the time of writing is 1.75. You must use the LaTeX sigconf proceedings template as the conference organizers are unable to process final submissions in other formats. In case of problems with the templates, contact ACM's TeX support team at Aptara. Authors should note ACM's statement on author's rights which apply to final papers. Submitted papers should meet the requirements of ACM's plagiarism policy.

Requirements for publication

At least one author of each accepted submission will be expected to attend and present the work at the conference. The pc chair may retract a paper that is not presented. The pc chair may also retract a paper if complaints about the paper's correctness are raised which cannot be resolved by the final paper deadline.

Review process

The reviewing is single-blind.



PPDP 2021 Proceedings
Proceedings will be published in the ACM International Conference Proceedings Series under ISBN 978-1-4503-8689-0, and will be available in the ACM Digital Library.


Program co-Chair

Silvia Ghilezan
University of Novi Sad
Mathematical Institute SASA Belgrade

Local Chair

Niccolò Veltri
Logic and Semantics Group
Tallinn University of Technology

In Cooperation with

AMC In-cooperation