July 2025 - Haskell-Cafe

Combining RequiredTypeArguments and type class methods?
by Viktor Dukhovni 13 Jul '25

13 Jul '25

The user guide documentation of RequiredTypeArguments highlights a hypothetical alternative to the interface of the `sizeOf` method of the Storable class: https://downloads.haskell.org/ghc/9.12.2/docs/users_guide/exts/required_typ… sizeOf :: forall a -> Storable a => Int If sizeOf had this type, we could write sizeOf Bool without passing a dummy value. This is fine in isolation, but how would this actually work in a type class method definition? The below naïve attempt does not work: {-# LANGUAGE AllowAmbiguousTypes #-} {-# LANGUAGE RequiredTypeArguments #-} class MyStorable a where sizeOf :: forall a -> MyStorable a => Int instance MyStorable Bool where sizeOf (type Bool) = 1 --- • Expected kind ‘k’, but ‘Bool’ has kind ‘*’ ‘k’ is a rigid type variable bound by the type signature for: sizeOf :: forall {k}. forall (a1 :: k) -> MyStorable a1 => Int at /tmp/foo.hs:8:5-10 • In the type ‘Bool’ In a type argument: Bool In the pattern: type Bool • Relevant bindings include sizeOf :: forall (a :: k) -> MyStorable a => Int (bound at /tmp/foo.hs:8:5) | 8 | sizeOf (type Bool) = 1 | ^^^^ Is the hypothetical `sizeOf` actually realisable as a type class method? Or can it only be a module-level wrapper? Something like the below, which does work? {-# LANGUAGE RequiredTypeArguments #-} class MyStorable a where _sizeOf :: a -> Int instance MyStorable Bool where _sizeOf _ = 1 instance MyStorable Int where _sizeOf _ = 8 sizeOf :: forall a -> MyStorable a => Int sizeOf a = _sizeOf (undefined :: a) Is it possible to avoid the (undefined :: a) term and somehow use TypeApplications here, with an "ambiguous" `_sizeOf` method? class MyStorable a where _sizeOf :: Int -- Viktor. 🇺🇦 Слава Україні!

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ZuriHac 2025 Videos Online
by Farhad D. Mehta 09 Jul '25

09 Jul '25

Hi Everyone It was great to see you at [ZuriHac 2025](https://zfoh.ch/zurihac2025/). In case you couldn’t attend, or would like to relive the magic, the recordings from the event are now online at: [ZuriHac 2025 Playlist – Talks, Panels & Projects from the Haskell Community](https://www.youtube.com/playlist?list=PLOvRW_utVPVlFEXuyaIVILO1t… In this playlist, you'll find talks on: 🎓 Education, Pedagogy and Community - Zoe Kooyman on freedom-preserving software, ethics, and empowering developers through appropriate software licensing - Richard Southwell on category theory - Tom Ellis on the history of effect systems - Brent Yorgey on competitive programming - Pedro Abreu interviewing participants on their impressions on ZuriHac, and why they love (and hate) Haskell ⚙️ Tooling & Infrastructure - Cheng Shao on GHC’s WebAssembly backend and runtime architecture - Malte Ott on reproducible Haskell deployment using Nix and Flakes - Alex Vieth on managing risk - Panel discussion covering industry adoption, tooling, onboarding, and language design 💡 Programming Concepts & Philosophy - Lennart Augustsson on MicroHs, compiler simplicity, the history of Haskell and functional programming, dependent types, and writing trustworthy code - Shared focus across talks on laziness, purity, composability, and types as documentation - Emphasis on keeping Haskell both powerful and welcoming for newcomers 🛠️ Community Projects Lightning demos from the Project Presentation session: Inline Verilog support, performance benchmarks, Git conflict tooling, HLS improvements, smart contracts via linear types, education platforms, games, and more 🏛️ Opening Ceremony Highlights - OST’s and ZfoH's ongoing role as host and supporter of open functional programming - Short presentations from supporters and community partners - Project pitches covering Haskell in science, hardware, industry, and education Whether you want to learn, get inspired, or dive deep into modern Haskell development — this playlist captures the energy, ideas, and innovation that define ZuriHac. Find out how Haskell is shaping the future of programming. Just try not to watch it all in one sitting: There is still some time to bridge until the next ZuriHac. Thanks to everyone who actively participated and contributed to the event with their talks, tracks, and other help! The other organisers and I look forward to seeing you at [ZuriHac 2026](https://zfoh.ch/zurihac2026/). Best regards Farhad Mehta (on behalf of the ZfoH & OST)

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Fifth International Conference on Digital Data Processing (DDP 2025)
by edprocess＠dline.info 07 Jul '25

07 Jul '25

Fifth International Conference on Digital Data Processing (DDP 2025) University of Bedfordshire. Luton. (Near London) UK. August 18-20, 2025 (www.socio.org.uk/ddp) (IEEE Publication) (Virtual Presentation/Physical) As technology advances in different sub-domains of computing, data-driven models are becoming increasingly important. The data-dependent world now faces many challenges in terms of data accuracy and data privacy. High-impact advancements include machine learning, artificial intelligence, deep learning and many more. Data is growing exponentially in terms of diversity and complexity. One organization or industry processes over a few million transactions per hour and stores hundreds of billions of data. We live in a world with a great need for more efficient data analysis and processing. Data analytics can reveal hidden patterns, complex relationships, internal information relations, and even segmentation. Data applications have opened up new possibilities in every aspect of our lives. Studying data and its structure, dynamics, and modern data technologies is an ongoing process. There is a great deal of literature and research on data management, but it does not address the data processing needs. Many studies focus on developing models and systems for analysing large datasets. Data analysis leads to application domains that have a systematic impact on decisions. The knowledge gained from the data analysis enables the generation of critical information for multiple domains. In this conference, we review and discuss the latest trends in data management, the opportunities and challenges, and how they have affected organizations' ability to develop effective business and technology strategies and stay up-to-date in data technology. We also highlight current open research directions in data analytics that need further attention. The proposed conference will discuss topics not limited to Data applications in various domains and activities Data in cloud Real-world data processing Data inaccuracy and reliability issues Data Ecosystem Business Analytics New data analytics techniques Physical and management challenges Synthetic data Data synthesis Crowdsourcing and Sensing Data modelling Deep learning techniques Data fusion Descriptive analytics, Diagnostic analytics, Predictive Analytics, and Prescriptive analytics Machine learning impact on data processing Network optimization Data in Biomedical Engineering Data in Materials science and mechanics Data handling and applications in domains Wireless Networking Data Management Data of Electronic & Embedded Systems Multi-media Systems Data Artificial Intelligence Models and Systems Data E-Computing Data Renewable Energies Data General Chair General Chair Ezendu Ariwa Warwick University, UK Program Chairs Youshan Zhang, Yeshiva University, USA Simon Fong, University of Macau, Macau Duong Van Hieu, Tien Giang University, Vietnam Program Co-chairs Martin Lopez Nores, University of Vigo, Spain Frankie Wilson, University of Oxford. UK Publicity Chair Mohsin Beniysa, Abdelmalek Essaâdi University, Morocco Publications All accepted and presented papers will be submitted to IEEE Xplore for publication and indexing. The DDP 2025 has co-located workshops. Modified versions of the papers will appear in the following journals. Journal of Digital Information Management International Journal of Computational Linguistics Open Information Science Important Dates Submission of Papers: July 15, 2025 Notification of Acceptance/Rejection: August 10, 2025 Camera-ready: August 31, 2025 Registration: August 15, 2025 Conference Dates: August 18-20, 2025 Post-Conference Proceedings Release: November 30, 2025 We'll be able to bring the post-conference proceedings only. Based on the review of the submissions, we issue a notification, and the authors can present using PPT files, for which a full-text camera-ready version is not required. With the help of feedback received during the conference and reviews, the authors can update their papers and submit the camera-ready. Paper submission Papers should follow the IEEE template. Submissions at http://socio.org.uk/ddp/paper-submission/ Contact: ddp(a)socio.org.uk

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POPL 2026 Last Call for Papers
by Ningning Xie 04 Jul '25

04 Jul '25

PACMPL Issue POPL 2026 seeks contributions on all aspects of programming languages and programming systems, both theoretical and practical. Authors of papers published in PACMPL Issue POPL 2026 will be invited to present their work in the POPL conference in January 2026, which is sponsored by ACM SIGPLAN, in cooperation with ACM SIGACT and ACM SIGLOG. POPL 2026 Website: https://popl26.sigplan.org/ Call for Papers: https://conf.researchr.org/track/POPL-2026/POPL-2026-popl-research-papers Submission deadline: July 10 2025 AOE Double-Blind Review FAQ: https://conf.researchr.org/track/POPL-2026/POPL-2026-popl-research-papers#d… ### Organization Conference Location: Rennes, France Conference Dates: January 11-17, 2026 General Chair: Sandrine Blazy, University of Rennes Program Chair: Suresh Jagannathan, Purdue University Program Committee: https://popl26.sigplan.org/committee/POPL-2026-popl-research-papers-program… ### Scope Principles of Programming Languages (POPL) is a forum for the discussion of all aspects of programming languages and programming systems. Both theoretical and experimental papers are welcome, on topics ranging from formal frameworks to experience reports. We seek submissions that make principled, enduring contributions to the theory, design, understanding, implementation, or application of programming languages. ### Evaluation Criteria The Review Committee will evaluate the technical contribution of each submission as well as its accessibility to both experts and the general POPL audience. All papers will be judged on significance, originality, relevance, correctness, and clarity. Each paper must explain its scientific contribution in both general and technical terms, identifying what has been accomplished, explaining why it is significant, and comparing it with previous work. Advice on writing technical papers can be found on the SIGPLAN author information page: https://www.sigplan.org/Resources/Author/. Deadlines and formatting requirements, detailed below, will be strictly enforced. ### Double-Blind Reviewing Process POPL 2026 will use a full double-blind reviewing process (similar to the one used in recent years (POPL 2023 - 2025) but different from the lightweight double-blind process used before then). This means that identities of authors will not be made visible to reviewers until after conditional-acceptance decisions have been made, and then only for the conditionally-accepted papers. The use of full double-blind reviewing has several consequences for authors. * **Submissions**: Authors must omit their names and institutions from their paper submissions. In addition, references to authors’ own prior work should be in the third person (e.g., not “We build on our previous work …” but rather “We build on the work of …”). * **Supplementary material**: Authors are permitted to provide supplementary material (e.g., detailed proofs, proof scripts, system implementations, or experimental data) along with their submission, which reviewers may (but are not required to) examine. This material may take the form of a single file, such as a PDF or a tarball. Authors must fully anonymize any supplementary material. * **Author response**: In responding to reviews, authors should not say anything that reveals their identity, since author identities will not be revealed to reviewers at that stage of the reviewing process. * **Dissemination of work under submission**: Authors are welcome to disseminate their ideas and post draft versions of their paper(s) on their personal website, institutional repository, or arXiv (reviewers will be asked to turn off arXiv notifications during the review period). But authors should not take steps that would almost certainly reveal their identities to members of the Program Committee, e.g., directly contacting PC members or publicizing the work on widely-visible social media or major mailing lists used by the community. The purpose of the above restrictions is to help the Program Committee and external reviewers come to a judgment about the paper without bias, not to make it impossible for them to discover the authors’ identities if they were to try. In particular, nothing should be done in the name of anonymity that weakens the quality of the submission. However, there are occasionally cases where adhering to the above restrictions is truly difficult or impossible for one reason or another. In such cases, the authors should contact the Program Chair to discuss the situation and how to handle it. The FAQ on Double-Blind Reviewing addresses many common scenarios and answers many common questions about this topic. But there remain many grey areas and trade-offs. If you have any doubts about how to interpret the double-blind rules or you encounter a complex case that is not clearly covered by the FAQ, please contact the Program Chair for guidance. ### Evaluation Process POPL 2026 will have five Associate Chairs who will help the PC Chair monitor reviews, solicit external expert reviews for submissions when there is not enough expertise on the committee, and facilitate reviewer discussions. As in previous years, authors will have a multi-day period to respond to reviews, as indicated in the Important Dates table. Responses are optional. A response must be concise, addressing specific points raised in the reviews; in particular, it must not introduce new technical results. Reviewers will write a short reaction to these author responses. The Review Committee (RC) will discuss papers electronically, and will use synchronous virtual meetings to discuss any papers for which there is disagreement among reviewers, in some cases soliciting additional input from other experts in the committee. There is no formal External Review Committee, though experts outside the committee may be consulted for some papers. Reviews will be accompanied by a short summary of the reasons behind the committee’s decision with the goal of clarifying the reasons behind the decision. To conform with ACM requirements for journal publication, all POPL papers will be conditionally accepted; authors will be required to submit a short description of the changes made to the final version of the paper, including how the changes address any requirements imposed by the Review Committee. That the changes are sufficient will be confirmed by the original reviewers prior to acceptance to POPL. Authors of conditionally accepted papers must submit a satisfactory revision to the Review Committee by the requested deadline or risk rejection. For additional information about the reviewing process, see: [Principles of POPL](https://www.sigplan.org/Conferences/POPL/Principles/), a presentation of the underlying organizational and reviewing policies for POPL. For POPL 2026, policies specified in this Call for Papers supersede those in the Principles of POPL document. ### Submission Site Information The submission site is https://popl26.hotcrp.com. Authors can submit multiple times prior to the deadline. Only the last submission will be reviewed. There is no abstract deadline. The submission site requires entering author names and affiliations, relevant topics, and potential conflicts. Addition or removal of authors after the submission deadline will need to be approved by the Program Chair (as this kind of change potentially undermines the goal of eliminating conflicts during paper assignment). The submission deadline is 11:59PM July 10, 2025 anywhere on earth (AOE): https://en.wikipedia.org/wiki/Anywhere_on_Earth ### Conflicts of Interest For each submission, the authors must make sure that they properly declare all potential conflicts of interest for all of the authors of that submission. This includes marking PC conflicts as well as “Other Conflicts (external)”. A conflict caught late in the reviewing process leads to a voided review which may be infeasible to replace. Conflicts should be declared between an adviser and an advisee (e.g., Ph.D., post-doc; forever), between an author and a co-author (papers and proposals; for two years), between people at the same institution (branches of large companies or different locations of research institutes are considered to be the same institution; for two years after leaving an institution), between people with financial conflicts of interest, and between friends or relatives. If a possible reviewer does not meet the above criteria, please do not identify him/her as conflicted. Doing so could be viewed as an attempt to prevent a qualified, but possibly skeptical reviewer from reviewing your paper. If you nevertheless believe that a reviewer who does not meet the above criteria is conflicted, or if you are unsure about a possible conflict, you may identify the person and send a note to the PC Chair. Declaring a spurious conflict with the aim of excluding otherwise qualified reviewers can be grounds for desk rejection. ### Submission Guidelines Prior to the paper submission deadline, authors should upload their full anonymized paper. Here are some key requirements concerning paper submissions: * Each paper should have no more than **25 pages of text, excluding bibliography**, using the PACMPL format (specifically, the `acmart` LaTeX class with `acmsmall` option). It is a single-column page layout with a 10 pt font, 12 pt line spacing, and wider margins than recent POPL page layouts. In this format, the main text block is 5.478 in (13.91 cm) wide and 7.884 in (20.03 cm) tall. Use of a different format (e.g., smaller fonts or a larger text block) is grounds for summary rejection. The PACMPL template for LaTeX can be found at the [SIGPLAN author information page](https://www.sigplan.org/Resources/Author/), and further information about PACMPL submissions can be found on the [PACMPL author guidelines page](https://dl.acm.org/journal/pacmpl/author-guidelines). PACMPL does not support submissions in Microsoft Word. * We strongly encourage use of the `review` and `screen` options in order to make submissions easier to review. * Authors may choose which citation format they wish to use, which can be either author-year (the mandate for final versions in previous years) or numeric. * Submissions should be in PDF and printable on both US Letter and A4 paper. Papers may be resubmitted to the submission site multiple times up until the deadline, but the last version submitted before the deadline will be the version reviewed. * Submitted papers must adhere to the [SIGPLAN Republication Policy](https://www.sigplan.org/Resources/Policies/Republication/) and the [ACM Policy on Plagiarism](https://www.acm.org/publications/policies/plagiarism-overview ). Concurrent paper submissions to other conferences, workshops, journals, or similar forums of publication are not allowed. * Authors are free to submit supplementary material along with their submissions, but it must be fully anonymized. * Authors must list all their conflicts of interest (both PC conflicts and external conflicts) in the HotCRP submission form. * Authors may include additional information in a field of the HotCRP submission form labeled "Confidential Comments for the Program Chair". This information need not be anonymized. It can be used to inform the Program Chair, for example, about sensitive issues concerning a conflict with a PC member or about supplementary material that cannot be anonymized. It is left to the discretion of the Program Chair what to do with this information. * If for some reason an author feels uncomfortable discussing a sensitive issue with the Program Chair (or communicating via the "Confidential Comments" field in HotCRP), they should feel free to get in touch instead with any of the Associate Chairs, with whom they can discuss the issue in confidence. * Submissions from PC members and Associate Chairs (except the Program Chair) are permitted and will not be handled any differently than other submissions. This is in accordance with a recent change in policy approved by the SIGPLAN Executive Committee: SIGPLAN conferences that use full double-blind review and whose PCs have at least 50 members need not hold PC submissions to a higher standard. ### Artifact Evaluation for Accepted Papers Authors of conditionally accepted papers will be invited to formally submit supporting materials to the Artifact Evaluation process. Artifact Evaluation is run by a separate committee whose task is to assess how the artifacts support the work described in the papers. Artifact submission is strongly encouraged but voluntary and will not influence the final decision regarding the papers. Papers that go through the Artifact Evaluation process successfully will receive a seal of approval printed on the papers themselves. Authors of accepted papers are encouraged to make these materials publicly available upon publication of the proceedings, by including them as “source materials” in the ACM Digital Library. ### Copyright, Publication, and Presentation As a Gold Open Access journal, PACMPL is committed to making peer-reviewed scientific research free of restrictions on both access and (re-)use. Authors are strongly encouraged to support libre open access by licensing their work with the [Creative Commons Attribution 4.0 International (CC BY) license](https://creativecommons.org/licenses/by/4.0/), which grants readers liberal (re-)use rights. Authors of accepted papers will be required to choose one of the following publication rights: * Author licenses the work with a [Creative Commons license](https://creativecommons.org/), retains copyright, and (implicitly) grants ACM non-exclusive permission to publish (suggested choice). * Author retains copyright of the work and grants ACM a non-exclusive permission to publish license. * Author retains copyright of the work and grants ACM an exclusive permission to publish license. * Author transfers copyright of the work to ACM. These choices follow from ACM Copyright Policy and ACM Author Rights, corresponding to ACM’s “author pays” option. While PACMPL may ask authors who have funding for open-access fees to voluntarily cover the article processing charge, payment is not required for publication. PACMPL and SIGPLAN continue to explore the best models for funding open access, focusing on approaches that are sustainable in the long-term while reducing short-term risk. All papers will be archived by the ACM Digital Library. Authors will have the option of including supplementary material with their paper. The official publication date is the date the proceedings 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. Authors of accepted papers are encouraged to give a short talk (roughly 25 minutes long) at the conference, according to the conference schedule. Authors who wish to present but who cannot attend in person will be provided with some option for remote presentation, as well as some mechanism for remote interaction with conference participants. ### Important update on ACM’s new open access publishing model for 2026 ACM Conferences! Starting January 1, 2026, ACM will fully transition to Open Access. All ACM publications, including those from ACM-sponsored conferences, will be 100% Open Access. Authors will have two primary options for publishing Open Access articles with ACM: the ACM Open institutional model or by paying Article Processing Charges (APCs). With over 1,800 institutions already part of ACM Open, the majority of ACM-sponsored conference papers will not require APCs from authors or conferences (currently, around 70-75%). Authors from institutions not participating in ACM Open will need to pay an APC to publish their papers, unless they qualify for a financial or discretionary waiver. To find out whether an APC applies to your article, please consult the list of participating institutions in ACM Open and review the APC Waivers and Discounts Policy. Keep in mind that waivers are rare and are granted based on specific criteria set by ACM. Understanding that this change could present financial challenges, ACM has approved a temporary subsidy for 2026 to ease the transition and allow more time for institutions to join ACM Open. The subsidy will offer: $250 APC for ACM/SIG members and $350 for non-members. This represents a 65% discount, funded directly by ACM. Authors are encouraged to help advocate for their institutions to join ACM Open during this transition period. This temporary subsidized pricing will apply to all conferences scheduled for 2026. ### Distinguished Paper Awards At most 10% of the accepted papers of POPL 2026 will be designated as Distinguished Papers. This award highlights papers that the Review Committee thinks should be read by a broad audience due to their relevance, originality, significance, and clarity. The selection of the distinguished papers will be made based on the final version of the paper and through an additional review process.

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ICFP/SPLASH 2025: call for volunteers
by ICFP Publicity 03 Jul '25

03 Jul '25

ICFP/SPLASH 2025 are looking for volunteers to help with the organization and smooth running of the conference. In exchange, volunteers receive: - Free conference registration (including banquet) - Free lunches and refreshments during breaks - Volunteer shirt - Admission to all social events *Note: Travel and accommodation are not covered.* *Who can apply? *Anyone can apply. Priority will be given to junior members of the community, such as students in computer science or related fields. *Availability. *Volunteers must be available for at least five (5) full days between October 12–18, 2025, and should be ready to help with various tasks during that period. Some pre-conference coordination and training may be required. We welcome both virtual and in-person volunteers from all time zones. *Apply here: *https://tinyurl.com/splashifcp25-sv-application *More details: * https://conf.researchr.org/track/icfp-splash-2025/icfp-splash-2025-voluntee…

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Postdoctoral Researcher Position at the University of Tartu
by Danel Ahman 01 Jul '25

01 Jul '25

The Laboratory for Software Science at the Institute of Computer Science at the University of Tartu is seeking an aspiring talented and hard-working young scientist to fill a postdoctoral position. The successful candidate will work with Dr. Danel Ahman on topics at the intersection of dependent and refinement types, computational effects (in particular, algebraic effects and effect handlers) and type-and-effect systems, and modal types, with specifics determined based on the common interests of the candidate and the supervisor. Candidates from other related PL areas are also encouraged to apply. Our group currently consists of 4 faculty, 3 (soon 4) PhD students, and soon 1 more postdoc (in addition to this advertisement), with expertise in a wide range of PL topics, ranging from type systems and semantics of programming languages, to abstract interpretation based automated verification tools, to various topics in category theory. Consult our webpage for more information on us: https://sws.cs.ut.ee<https://sws.cs.ut.ee/>. In Estonia, we also have close ties and regularly collaborate with the Algebra Group (https://math.ut.ee/en/content/algebra) at the Institute of Mathematics and Statistics at the University of Tartu, and the Logic and Semantics Group (https://cs.ioc.ee/lsg/) at the Tallinn University of Technology. We also collaborate actively internationally. The position is for up to 18 months, with a start date on 1 Oct 2025 or soon thereafter. The monthly gross salary will start from 2700 EUR depending on the experience of the candidate. The salary includes coverage by the national health insurance system, paid annual leave etc. A salary like this ensures a high standard of living in Estonia. Knowledge of Estonian is not required for this position, and for living in Tartu in general. The working language of our group is English. For more information about life in Tartu and more broadly in Estonia, see https://visittartu.com<https://visittartu.com/> and https://visitestonia.com/en. The job advertisement and application instructions can be found at https://candidate.recrur.com/public/jobad/EN/6b969e7f-8 The application deadline is 01 Aug 2025. Interested candidates should contact Danel Ahman (danel.ahman(a)ut.ee<mailto:danel.ahman@ut.ee>) with any questions.

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