May 2025 - Haskell-Cafe

Haskell Symposium 2025 Call for Papers (deadline June 9 AOE)
by Ningning Xie 29 May '25

29 May '25

======================================================================== Haskell Symposium 2025 Call for Papers Thu 16 - Fri 17 Oct 2025, Singapore https://conf.researchr.org/home/icfp-splash-2025/haskellsymp-2025 ======================================================================== The ACM SIGPLAN Haskell Symposium 2025 will be co-located with the 2025 International Conference on Functional Programming (ICFP) and the 2025 International Conference on Systems, Programming, Languages and Applications: Software for Humanity (SPLASH). The Haskell Symposium presents original research on Haskell, discusses practical experience and future development of the language, and promotes other forms of declarative programming. Submission deadline: 9 June 2025 (Mon) Notification: 17 July 2025 (Thu) Deadlines are valid anywhere on Earth. Papers should be submitted through HotCRP at: https://haskell25.hotcrp.com/ Topics of interest include: * Language design, with a focus on possible extensions and modifications of Haskell as well as critical discussions of the status quo; * Theory, such as formal semantics of the present language or future extensions, type systems, effects, metatheory, and foundations for program analysis and transformation; * Implementations, including program analysis and transformation, static and dynamic compilation for sequential, parallel, and distributed architectures, memory management, as well as foreign function and component interfaces; * Libraries, that demonstrate new ideas or techniques for functional programming in Haskell; * Tools, such as profilers, tracers, debuggers, preprocessors, and testing tools; * Applications, to scientific and symbolic computing, databases, multimedia, telecommunication, the web, and so forth; * Functional Pearls, being elegant and instructive programming examples; * Experience Reports, to document general practice and experience in education, industry, or other contexts; * Tutorials, to document how to use a particular language feature, programming technique, tool or library within the Haskell ecosystem; * System Demonstrations, based on running software rather than novel research results. Keynote Speakers ================= * Richard A. Eisenberg * Simon Peyton Jones Program Committee ================= Andreas Abel Gothenburg University Patrick Bahr IT University of Copenhagen Matthew Fluet Rochester Institute of Technology Adam Gundry Well-Typed LLP Xuejing Huang IRIF Hideya Iwasaki Meiji University Patricia Johann Appalachian State University Hsiang-Shang 'Josh' Ko Institute of Information Science, Academia Sinica András Kovács University of Gothenburg and Chalmers University of Technology Andres Löh Well-Typed LLP J. Garrett Morris (co-chair) University of Iowa Liam O'Connor Australian National University Maciej Piróg University of Wrocław Arnaud Spiwack Tweag Meng Wang University of Bristol Li-yao Xia Inria Ningning Xie (co-chair) University of Toronto Gergő Érdi Standard Chartered Bank

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Best way to implement "scoped exceptions"?
by Tom Ellis 27 May '25

27 May '25

I'd like to implement "scoped exceptions"[1], that is, a combinator of type withScopedException :: ((forall a. e -> IO a) -> IO r) -> IO (Either e r) so I can use exceptions in a convenient way, without having to set up fragile "action at a distance" based on the type of the thing I'm throwing and catching, for example: scopedExceptionExample :: IO (Either String (Either Int Void)) scopedExceptionExample = do withScopedException $ \throw1 -> withScopedException $ \throw2 -> if (1 :: Int) < 0 then throw1 "Hello" else throw2 1234 -- ghci> scopedExceptionExample -- Right (Left 1234) Here's a hacky way of doing it, based on tagging each exception with a unique value, and then filtering when handling: data MyException where MyException :: e -> Data.Unique.Unique -> MyException instance Show MyException where show _ = "<MyException>" instance Exception MyException withScopedException :: ((forall a. e -> IO a) -> IO r) -> IO (Either e r) wiathScopedException f = do fresh <- Data.Unique.newUnique flip tryJust (f (\e -> throwIO (MyException e fresh))) $ \case MyException e tag -> -- unsafeCoerce is very unpleasant if tag == fresh then Just (unsafeCoerce e) else Nothing This is the approach taken by the effectful library[2]. But is there a better way? Can I persuade GHC's RTS to work like this directly? Tom [1] I don't know if these already have a name [2] https://hackage.haskell.org/package/effectful-core-2.2.1.0/docs/src/Effectf…

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[ANN] Copilot 4.4
by Ivan Perez 25 May '25

25 May '25

Hi everyone!! We are really excited to announce Copilot 4.4 [1,2]. Copilot is a stream-based EDSL in Haskell for writing and monitoring embedded C programs, with an emphasis on correctness and hard realtime requirements. Copilot is typically used as a high-level runtime verification framework, and supports temporal logic (LTL, PTLTL and MTL), clocks and voting algorithms. Compilation to Bluespec, to target FPGAs, is also supported. Copilot is NASA Class D open-source software, and is being used at NASA in drone test flights. Through the NASA tool Ogma [3] (also written in Haskell), Copilot also serves as a programming language and runtime framework for NASA's Core Flight System, Robot Operating System (ROS2), FPrime (the software framework used in the Mars Helicopter). Ogma now supports producing flight and robotics applications directly in Copilot, not just for monitoring, but for implementing the logic of the applications themselves. This release introduces several updates, bug fixes and improvements to Copilot: - The Kind2 backend is now able to distinguish between existentially and universally quantified properties. - The fields of the existential record type Copilot.Core.Type.UType have now been removed. - The build status icon in the README has now been corrected to show the current build status. The new implementation is compatible with versions of GHC from 8.6 to 9.12. This release has been made possible thanks to key submissions from Ryan Scott (Galois) and Kyle Beechly, both recurrent contributors to Copilot. We are grateful to them for their contributions, and for making Copilot better every day. For details on this release, see [1]. As always, we're releasing exactly 2 months since the last release. Our next release is scheduled for July 7th, 2025. We want to remind the community that Copilot is now accepting code contributions from external participants again. Please see the discussions and the issues in our github repo [4] to learn how to participate. Current emphasis is on using Copilot for full data processing applications (e.g, system control, arduinos, rovers, drones), merging stable features (i.e., visualizer, Bluespec backend, verifier) into the mainline, improving usability, performance, and stability, increasing test coverage, removing unnecessary dependencies, hiding internal definitions, formatting the code to meet our new coding standards, and simplifying the Copilot interface. Users are encouraged to participate by opening issues, asking questions, extending the implementation, and sending bug fixes. Happy Haskelling! Ivan -- [1] https://github.com/Copilot-Language/copilot/releases/tag/v4.4 [2] https://hackage.haskell.org/package/copilot [3] https://github.com/nasa/ogma [4] https://github.com/Copilot-Language/copilot

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2nd CfP: Functional Software Architecture (FUNARCH, Deadline June 16)
by Michael Sperber 18 May '25

18 May '25

====================================================================== *** FUNARCH 2025 -- CALL FOR PAPERS *** Third ACM SIGPLAN Workshop on Functional Software Architecture - FP in the Large 17th October 2025, Singapore Co-located with ICFP 2025 https://functional-architecture.org/events/funarch-2025/ ====================================================================== TIMELINE: Paper submission 16th June 2025 Author notification 21st July 2025 Camera ready copy 25th August 2025 Workshop 17th October 2025 BACKGROUND: "Functional Software Architecture" refers to methods of construction and structure of large and long-lived software projects that are implemented in functional languages and released to real users, typically in industry. The goals for the workshop are: - To assemble a community interested in software architecture techniques and technologies specific to functional programming; - To identify, categorize, and document topics relevant to the field of functional software architecture; - To connect the functional programming community to the software architecture community to cross-pollinate between the two. The workshop follows on from the Functional Software Architecture open space that was held at ICFP 2022 in Slovenia. SCOPE: The workshop seeks submissions in a range of categories: - You're a member of the FP community and have thought about how to support programming in the large, for example by framing functional ideas in architectural terms or vice verse, comparing different languages in terms of their architectural capabilities, clarifying architectural roles played by formal methods, proof assistants and DSLs, or observing how functional concepts are used in other language and architecture communities. Great, submit a research paper! - You're a member of the architecture community, and have thought about how your discipline might help functional programmers, for example by applying domain-driven design, implementing hexagonal architecture, or designing self-contained systems. Excellent, submit a research paper! - You've worked on a large project using functional programming, and it's worked out well, or terribly, or a mix of both; bonus points for deriving architectural principles from your experience. Wonderful, submit an experience report! - You know a neat architectural idiom or pattern that may be useful to others developing large functional software systems. Fabulous, submit an architectural pearl! - You have something that doesn't fit the above categories, but that still relates to functional software architecture, such as something that can be written up, or that could be part of the workshop format like a panel debate or a fishbowl. Superb, submit to the open category! Research papers should explain their research contributions in both general and technical terms, identifying what has been accomplished, explaining why it is significant, and relating it to previous work, and to other languages where appropriate. Experience reports and architectural pearls need not necessarily report original research results. The key criterion for such papers is that they make a contribution from which others can benefit. It is not enough simply to describe a large software system, or to present ideas that are specific to a particular system. Open category submissions that are not intended for publication are not required to follow the formatting guidelines, and can submit in PDF, word or plain text format as preferred. Not knowing what kinds of submissions we will receive, we cannot be specific as to how they will be evaluated. However, submissions that seem likely to stimulate discussion around practices in functional architecture are encouraged. If you are unsure whether your contribution is suitable, or if you need any kind of help with your submission, please email the program chairs (Jeff (jmy6342(a)gmail.com) and Christine (christine.rizkallah(a)unimelb.edu.au)) Papers must be submitted by 16th June 2025 using the hotcrp submission page (https://funarch25.hotcrp.com/) Formatting: submissions intended for publication must be in PDF format and follow the ACM SIGPLAN style guidelines, using the acmart format and the sigplan sub-format. Please use the review option when submitting, as this enables line numbers for easy reference in reviews. For further details, see SIGPLAN's author information: http://www.sigplan.org/Resources/Author/#acmart-format If your submission is not a research paper, please mark this using a subtitle (Experience Report, Architectural Pearl, Open Category). Length: submissions must adhere to the limits specified below. However, there is no requirement or expectation that all pages are used, and authors are encouraged to strive for brevity. Research papers 5 to 12+ pages Architectural pearls 5 to 12 pages Experience reports 3 to 6 pages Open category 1 to 6 pages Publication: The proceedings of FUNARCH 2024 will be published in the ACM Digital Library, and authors of accepted papers are required to agree to one of the standard ACM licensing options. Accepted papers must be presented at the workshop by one of the authors, but in special cases we may consider remote presentation. The official publication date is the date the papers are made available in the ACM Digital Library. This date may be up to two weeks prior to the first day of the conference. The official publication date affects the deadline for any patent filings related to published work. PROGRAM CHAIRS: Jeffrey Young (Unaffiliated) Cristine Rizkallah (University of Melbourne) PROGRAM COMMITTEE: Isabella Stilkerich (Schaeffler Technologies) Ryan Scott (Galois) Facundo Dominguez (Tweag) J. Garrett Morris (University of Iowa) Nada Amin (Harvard University) Tom Ellis (Groq) KC Sivaramakrishnan (IIT Madras and Tarides) Hidehiko Masuhara (Institute of Science Tokyo) WORKSHOP VENUE: Room to be determined. The workshop will be co-located with the ICFP 2025 conference at the Marina Bay Sands Convention Centre, Singapore.

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Fwd: CGO'26 - Call for Papers and first submission round
by Luisa Cicolini 17 May '25

17 May '25

ACM/IEEE International Symposium on Code Generation and Optimization (CGO 2026) Call for Papers - First Submission Deadline The Call for Papers<https://2026.cgo.org/track/cgo-2026-papers> is out for the next International Symposium on Code Generation and Optimization (CGO’26)<https://2026.cgo.org/>, taking place next year in Sydney, Australia. CGO provides a premier venue to bring together researchers and practitioners working at the interface of hardware and software on a wide range of optimization and code generation techniques and related issues. The conference spans the spectrum from purely static to fully dynamic approaches, and from pure software-based methods to specific architectural features and support for code generation and optimisation. The first submission round is coming up, with the following deadlines: * Paper Submission: 29 May 2025 * Author Rebuttal Period: 8–10 July 2025 * Paper Notification: 21 July 2025 For more information, please visit the CGO’26 website<https://2026.cgo.org/>. We look forward to receiving your submissions! Best, Luisa Cicolini

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ZuriHac 2025 Schedule Online
by Farhad D. Mehta 12 May '25

12 May '25

Dear Friends of Haskell, The schedule for ZuriHac 2025 is now online on https://zurihac.info ! This year’s keynote speakers include Lennart Augustson (who will talk about “MicroHs”, a Haskell compiler with a runtime system so small that is can run on a microcontroller), Tom Ellis (author of the Bluefin effect system), and Brent Yorgey (of “Diagrams” and “Swarm” fame, who will talk about competitive programming in Haskell). We also have a track on Category Theory, given by Richard Southwell (of YouTube fame), as well as a track on WASM+Haskell and Nix+Haskell given by Cheng Shao and Julian Arni respectively. The Beginners’ Track this year will be given by Andres Löh. Our website https://zurihac.info contains further information on keynotes and tracks and will be updated regularly. In case you have not registered yet, please do so ASAP via the link https://zureg.zfoh.ch/register (also on our website). Although registration is free for participants, it allows us to plan appropriately for the event: Jane Street is generously hosting a BBQ on Saturday evening, and we want to get the number of grillables correct. For the uninitiated: ZuriHac 2025 will take place Saturday 7 June – Monday 9 June 2025 as a physical event at the Rapperswil-Jona campus of the OST Eastern Switzerland University of Applied Sciences. ZuriHac is the biggest Haskell community event in the world: a completely free, three-day grassroots coding festival co-organized by the Zürich Friends of Haskell and the OST Eastern Switzerland University of Applied Science. It is not your standard conference with papers and presentations, but features fantastic keynotes, hands-on tracks, hacking on many of your favourite projects, and of course lots of socializing! Organizing ZuriHac would not be possible without the support of our sponsors and partners, including: * The Haskell Foundation * IOHK * Jane Street * OST * Tweag * Type Theory Forall * Well-Typed In case you would like to support ZuriHac, as a company or as an individual, please get in touch with us, we would be grateful: https://zfoh.ch/#donations. We hope to see you there! The Zurich Friends of Haskell

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State of redis-resp and redis-io?
by Magnus Therning 11 May '25

11 May '25

I've looked around for Haskell packages for Redis and found the API of redis-io nice. I did notice that neither it, not redis-resp which it depends on, have gotten much love the last few years. Does anyone here know what the state of these packages are? Are they abandoned, or simply "finished" and therefore needing very little maintenance? /M Magnus Therning OpenPGP: 0xAB4DFBA4 email: magnus(a)therning.org jabber: magnus(a)therning.org twitter: magthe http://therning.org/magnus

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application of the record field may fail
by Johannes Waldmann 09 May '25

09 May '25

Dear Cafe, (ignore following email, but perhaps the observation is still useful, the answer is to use `-Weverything`, which gives more than `-Wall`. Obviously.) For two constructors with fields of identical type but different name, data T = A {foo::()} | B {f00 ::()} GHC detects a typo in the field name ghci> f x = case x of A{f00 = f} -> f ; B {} -> () <interactive>:2:19: error: [GHC-53822] • Constructor ‘A’ does not have field ‘f00’ Good. Now changing the program slightly, ghci> f x = case x of A{} -> f00 x ; B {} -> () the program becomes statically correct. Can we get a warning here? (to detect the typo). This example is close to real code, not foo and f00 but something_longer and something_longerr. Yes I shoudn't do this, and make names more descriptive/distinct. And types! It's only a typo because it's not a type error. [EDIT] the answer is yes, we can, with -Weverything, <interactive>:9:24: warning: [GHC-17335] [-Wincomplete-record-selectors] The application of the record field ‘f00’ may fail for the following constructors: A this sounds over-cautious, because it _will_ fail (if evaluated at all). - J.W.

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Call for Participation: SLE 2025 - 18th ACM SIGPLAN International Conference on Software Language Engineering
by Andrei Chis 08 May '25

08 May '25

** Call for Participation ** 18th ACM SIGPLAN International Conference on Software Language Engineering (SLE 2025) 12-13 June 2025 Koblenz, Germany https://conf.researchr.org/home/sle-2025 https://www.sleconf.org/2025/ https://x.com/sleconf ------------------------------------------------------------------------ The ACM SIGPLAN International Conference on Software Language Engineering (SLE) is devoted to the principles of software languages: their design, their implementation, and their evolution. Like its predecessors, the 18th edition of the SLE conference, SLE 2025, will bring together researchers from different areas united by their common interest in the creation, capture, and tooling of software languages. It overlaps with traditional conferences on the design and implementation of programming languages, model-driven engineering, and compiler construction, and emphasises the fusion of their communities. To foster the latter, SLE traditionally fills a two-day program with a single track, with the only temporal overlap occurring between co-located events. --------------------------- Registration --------------------------- Registration happens via the STAF registration page Early Bird Registration Deadline is May 10th, 2025 https://conf.researchr.org/attending/staf-2025/staf-2025-registration --------------------------- Venue --------------------------- University of Koblenz https://conf.researchr.org/venue/sle-2025/staf-2025-venue --------------------------- Keynotes --------------------------- * Thorsten Berger, Ruhr University Bochum, Germany A New DSL Textbook in Town! * Friedrich Steimann, Fernuniversität in Hagen, Germany an Programming Be Liberated from the Functional Style? https://conf.researchr.org/home/sle-2025#Keynotes --------------------------- Awards --------------------------- During the conference, we will announce the following awards: * Distinguished paper: Award for the most notable paper, as determined by the PC chairs based on the recommendations of the program committee. * Distinguished artefact: Award for the artefact most significantly exceeding expectations, as determined by the AEC chairs based on the recommendations of the artefact evaluation committee. * Distinguished reviewer: Award for the programme committee member that produced the most useful reviews as assessed by paper authors. * Most Influential Paper: Award for the SLE 2015 paper with the greatest impact, as judged by the SLE Steering Committee. * COLA Award: 2024 Journal of Computer Languages Best Paper Award --------------------------- Accepted Papers --------------------------- * A Model-Driven Approach to Design, Generation, and Deployment of GUI Component Libraries Arkadii Gerasimov, Nico Jansen, Judith Michael, Bernhard Rumpe, Sebastian Will * AnyText: Incremental, left-recursive Parsing and Pretty-Printing from a single Grammar Definition with first-class LSP support Georg Hinkel, Alexander Hert, Niklas Hettler, Kevin Weinert * Boosting Parallel Parsing through Cyclic Operator Precedence Grammars Michele Chiari, Michele Giornetta, Dino Mandrioli, Matteo Pradella * Detecting Resource Leaks on Android with Alpakka Gustavo Amorim Santos, Alexandra Mendes, João Bispo * Dynamic Dependency-Based Purity Checking Anton Risberg Alaküla, Niklas Fors, Christoph Reichenbach * Exploratory, Omniscient, and Multiverse Diagnostics in Debuggers for Non-Deterministic Languages Damian Frölich, Tommaso Pacciani, L. Thomas van Binsbergen * Handling Grammar Cycles in the 1997 Standard ML Definition Elizabeth Scott, Adrian Johnstone * Integrating Model Checking into a Live Modeling Environment Joeri Exelmans, Ciprian Teodorov, Hans Vangheluwe * Lessons Learned: Challenges of Modular Language Design Alex Lüpges, Nico Jansen, Bernhard Rumpe * Optimal Language Design is Hard: A Case Study in ECMAScript (JavaScript) Standardization Philipp Riemer, Yury Nikulin, Ashley Claymore, Mikhail Barash * Optimize Effect Handling for Tail-resumption with Stack Unwinding Yuze Fu, Shigeru Chiba * Property-based Testing of Attribute Grammars José Nuno Macedo, Marcos Viera, João Saraiva * Scheduling the Construction and Interrogation of Scope Graphs Using Attribute Grammars Luke Bessant, Eric Van Wyk * (Semantic) Feature Model Differences with (Q)SAT Simone Heisinger, Maximilian Heisinger, Martina Seidl * TranspileJS, an Intelligent Framework for Transpiling JavaScript to WebAssembly José Pedro Ferreira, João Bispo, Susana Lima * Variability Fault Localization by Abstract Interpretation and its Application to SPL Repair Aleksandar S. Dimovski

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TyDe 2025 - Second Call for Papers
by Andras Kovacs 07 May '25

07 May '25

========================================================================= The Tenth International Workshop on TYPE-DRIVEN DEVELOPMENT Call for papers and extended abstracts Singapore, 12 October 2025 https://icfp25.sigplan.org/home/tyde-2025 ========================================================================= The Workshop on Type-Driven Development (TyDe) aims to show how static type information may be used effectively in the development of computer programs. Co-located with ICFP and SPLASH, this workshop brings together leading researchers and practitioners who are using or exploring types as a means of program development. We welcome all contributions, both theoretical and practical, on a range of topics including: * dependently typed programming; * generic programming; * design and implementation of programming languages, exploiting types in novel ways; * exploiting typed data, data dependent data, or type providers; * static and dynamic analyses of typed programs; * tools, IDEs, or testing tools exploiting type information; * pearls, being elegant, instructive examples of types used in the derivation, calculation, or construction of programs. ### Important dates ### * Mon 9 Jun 2025 (AoE): Submission deadline for papers and extended abstracts * Wed 16 Jul 2025: Notification of acceptance * Wed 30 Jul 2025: Submission of camera-ready papers to ACM * Sun 12 Oct 2025: Workshop ### Proceedings and Copyright ### We will have formal proceedings for full-length papers, published by the ACM. Accepted papers will be included in the ACM Digital Library. Authors must grant ACM publication rights upon acceptance, but may retain copyright if they wish. Authors are encouraged to publish auxiliary material with their paper (source code, test data, and so forth). The proceedings will be freely available for download from the ACM Digital Library from one week before the start of the conference until two weeks after the conference. The official publication date is the date the papers are made available in the ACM Digital Library. This date may be up to two weeks prior to the first day of the conference. The official publication date affects the deadline for any patent filings related to published work. ### Submission Details ### Submissions should fall into one of two categories: * regular research papers (12 pages); * extended abstracts (3 pages). The bibliography will not be counted against the page limits for either category. Regular research papers are expected to present novel and interesting research results, and will be included in the formal proceedings. Extended abstracts should report work in progress that the authors would like to present at the workshop. Extended abstracts will be distributed to workshop attendees but will not be published in the formal proceedings. We welcome submissions from PC members (with the exception of the two co-chairs), but these submissions will be held to a higher standard. Submission is handled through HotCRP: > https://tyde25.hotcrp.com All submissions should be in portable document format (PDF) and formatted using the ACM SIGPLAN style guidelines: > https://www.sigplan.org/Resources/Author/ Note that submissions should use the new ‘acmart’ format and the two-column ‘sigplan’ subformat (not to be confused with the one-column ‘acmsmall’ subformat). Extended abstracts must be submitted with the label ‘Extended Abstract’ clearly in the title. ### Presentations ### We expect that each accepted submission is presented at the workshop. Presentations are around 20 minutes plus questions. Remote presentation is possible. ### Participant Support ### Student attendees with accepted papers can apply for a SIGPLAN PAC grant to help cover participation-related expenses. PAC also offers other support, such as for child-care expenses during the meeting or for accommodations for members with physical disabilities. For details on the PAC program, see its web page: > https://www.sigplan.org/PAC/ ### Workshop Organization ### Organizing Committee: - András Kovács (University of Gothenburg and Chalmers University of Technology) - Yuting Wang (Shanghai Jiao Tong University, China) Program Committee: - Nathan Corbyn (University of Oxford, United Kingdom) - Stephen Dolan (Jane Street, United Kingdom) - Paul Downen (University of Massachusetts at Lowell, United States) - Brandon Hewer (University of Nottingham, United Kingdom) - Hongwei Xi (Boston University, United States) - Wen Kokke (University of Edinburgh, United Kingdom) - Yao Li (Portland State University, United States) - Hidehiko Masuhara (Institute of Science Tokyo, Japan) - Stefan Monnier (Université de Montréal, Canada) - Steven Ramsay (University of Bristol, United Kingdom) - Di Wang (Peking University, China) - Zhixuan Yang (Imperial College London, United Kingdom)

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