April 2022 - Haskell-Cafe

[ANN] cabal-clean (new tool)
by Andreas Abel 19 Aug '22

19 Aug '22

=== Wondering where your disk space goes with too many Haskell projects compiled with too many GHC versions? === https://hackage.haskell.org/package/cabal-clean https://github.com/andreasabel/cabal-clean `cabal-clean` is a small executable that removes outdated cabal build artifacts from `dist-newstyle`. A build tree is considered outdated if there is one with either - a newer version of the package you are building, or - a newer minor version of the GHC compiler. In contrast to `cabal clean`, the tool `cabal-clean` retains the latest build trees for each GHC major version. Thus, it is geared towards multi-GHC development. Example: (self-applied to cabal-clean's build directory) --- 3.7M ghc-8.8.4 /cabal-clean-0.1.20210815 --- 3.5M ghc-8.10.6/cabal-clean-0.1.20210815 --- 3.7M ghc-9.0.1 /cabal-clean-0.1.20210815 --- 3.5M ghc-8.10.6/cabal-clean-0.1.20210924 +++ 3.6M ghc-8.10.7/cabal-clean-0.1.20210924 +++ 3.7M ghc-9.0.1 /cabal-clean-0.1.20210924 The directories prefixed with --- will be deleted, the ones with +++ retained. Disclaimers: 1. cabal-clean does not check whether deletion will cause dangling references like broken symlinks etc. (Could happen if you created a symlink to an executable that resides in one of the deleted build directories.) 2. cabal-clean does not read nor utilize information from the .cabal file. 3. Calls `du` ("disk usage"), so, might not work on Windows. Enjoy, Andreas

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Package takeover request for rapid
by Markus Läll 19 May '22

19 May '22

Hi I would like to take over https://hackage.haskell.org/package/rapid The author of the package Ertugrul Söylemez, once an active member of the community perhaps best known for netwire, passed away in 2018. [1] The work required for the package thus far, and for which I've kept a fork for, is to bump version bounds as GHCs progress. [1] https://github.com/esoeylemez/rapid/pull/2#issuecomment-427065739 -- Markus Läll

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BX 2022 - Call for papers (deadline 14 May)
by Li-yao Xia 10 May '22

10 May '22

# Tenth International Workshop on Bidirectional Transformations (BX 2022) 8 July 2022, Nantes, France Part of STAF 2022 (5-8 July): https://staf2022.univ-nantes.io/ BX 2022 homepage: http://bx-community.wikidot.com/bx2022:home ## Overview Bidirectional transformations (BX) are a mechanism for maintaining the consistency between two or more related (and heterogeneous) sources of information (e.g., relational databases, software models and code, or any other artefacts following standard or domain-specific formats). The strongest argument in favour of BX is its ability to provide a synchronization mechanism that is guaranteed to be correct by construction. BX has been attracting a wide range of research areas and communities, with prominent presence at top conferences in several different fields (namely databases, programming languages, software engineering, and graph transformation). Nowadays, the fast-growing complexity of software- or data-intensive systems has forced industry and academia to use and investigate different development techniques to manage the many different aspects of the systems. Researchers are actively investigating the use of bidirectional approaches to tackle a diverse set of challenges with various applications including model-driven software development, visualization with direct manipulation, big data, databases, domain-specific languages, serializers, and data transformation, integration and exchange. BX 2022 is a dedicated venue for BX in all relevant fields and is part of a workshop series that was created in order to promote cross-disciplinary research and awareness in the area. As such, since its beginning in 2012, the workshop has rotated between venues in different fields. Papers for BX 2022 can be submitted on EasyChair: https://www.easychair.org/conferences/?conf=bx2022 ## Important Dates - Paper submission: 14 May, 2022 - Author notification: 28 May, 2022 - Workshop: 8 July, 2022 ## Topics The aim of the workshop is to bring together researchers and practitioners, established and new, interested in bx from different perspectives, including but not limited to: - bidirectional programming languages and frameworks - software development with BX - data and model synchronization - view updating - inter-model consistency analysis and repair - data/schema (or model/metamodel) co-evolution - coupled software/model transformations - inversion of transformations and data exchange mappings - domain-specific languages for BX - analysis and classification of requirements for BX - bridging the gap between formal concepts and application scenarios - analysis of efficiency of transformation algorithms and benchmarks - model-driven and model-based approaches - survey and comparison of BX technologies - case studies and tool support - applications and experiences of adopting BX in the real world ## Categories of Submissions Five categories of submissions are considered: 1. Full Research Papers (13-15 pages) - in-depth presentations of novel concepts and results - applications of bx to new domains - survey papers providing novel comparisons between existing bx technologies and approaches, case studies 2. Tool Papers (7-8 pages) - guideline papers presenting best practices for employing a specific bx approach (with a specific tool) - presentation of new tools or substantial improvements to existing ones - qualitative and/or quantitative comparisons of applying different bx approaches and tools 3. Experience Report (7-8 pages) - sharing experiences and lessons learned with bx tools/frameworks/languages - how bx is used in (research/industrial/educational) projects 4. Short Papers (5 pages) - work in progress - small focused contributions - position papers and research perspectives - critical questions and challenges for bx 5. Talk Proposals (2 pages) - proposed lectures about topics of interest for bx - existing work representing relevant contributions for bx - promising contributions that are not mature enough to be proposed as papers of the other categories ## Submission guidelines Papers should use the new CEUR-ART style, single column, available as an Overleaf page or as a zip archive: https://www.overleaf.com/read/gwhxnqcghhdt http://ceur-ws.org/Vol-XXX/CEURART.zip and must be submitted via EasyChair: https://www.easychair.org/conferences/?conf=bx2022 If your submission is not a Full Research Paper, please include the intended submission category in the Title field of EasyChair’s submission form. Tool papers, experience reports and short papers will be mapped to the short paper category in CEUR (having between 5-9 standard pages, 1 standard page = 2500 characters), whereas full research papers will be mapped to the regular paper category in CEUR (having at least 10 standard pages). The bibliography is excluded from the page limits. All papers are expected to be self-contained and well-written. Tool papers are not expected to present novel scientific results, but to document artifacts of interest and share bx experience/best practices with the community. Experience papers are expected to report on lessons learnt from applying bx approaches, languages, tools, and theories to practical application case studies. Extended abstracts should primarily provoke interesting discussion at the workshop and will not be held to the same standard of maturity as regular papers; short papers contain focused results, positions or perspectives that can be presented in full in just a few pages, and that correspondingly contain fewer results and that therefore might not be competitive in the full paper category. Talk proposals are expected to present work that is of particular interest to the community and worth a talk slot at the workshop. We strongly encourage authors to ensure that any (variants of) examples are present in the bx example repository at the time of submission, and, for tool papers, to allow for reproducibility with minimal effort, either via a virtual machine (e.g., via Share) or a dedicated website with relevant artifacts and tool access. All papers will be peer-reviewed by at least three members of the program committee. If a submission is accepted, at least one author is expected to participate in the workshop to present it. Authors of accepted tool paper submissions are also expected to be available to demonstrate their tool at the event. ## Proceedings The workshop proceedings (in a STAF 2022 joint volume for workshops), including all accepted papers (except talk proposals), shall be submitted after the conference to CEUR-WS.org for online publication. Pre-prints of all papers will be available via the workshop website at the beginning of the conference. In case of questions, please contact the PC chairs at bx2022(a)easychair.org. Best regards, Li-yao Xia, Vadim Zaytsev, Xiao He

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SPLASH 2022 Final Call for Workshop Proposals
by Andreea Costea 28 Apr '22

28 Apr '22

======================================================================== SPLASH 2022 Call for Workshops The ACM Conference on Systems, Programming, Languages, and Applications: Software for Humanity December 5-10, 2022, Auckland, New Zealand https://2022.splashcon.org/track/splash-2022-Workshops ======================================================================== We encourage proposals for workshops on any topic relevant to SPLASH. If there is a topic that you feel passionate about, and want to connect with others who have similar interests, submit a workshop proposal! We more than welcome new, and unconventional ideas for workshop formats. The following suggestions are a starting point: - Conference-style workshops allow participants to present their work to other domain experts. The smaller and more focused setting of a workshop allows for Q&A sessions and facilitates discussions. Presentations of work-in-progress are welcome. - Retreats act as a platform for experts to gather to tackle issues of a predetermined research agenda. Retreats are highly interactive and goal-oriented, allowing participants to address open challenges, explore new and uncharted ideas. - Agenda-setting workshops provide a forum for experts to determine a research agenda for a sub-field. - Other common activities at workshops include poster sessions, hands-on practical work, and focus groups. Workshops that include the presentation of research papers and that implement a SIGPLAN-approved selection process may archive proceedings in the ACM Digital Library. The workshop chairs will provide advice on achieving this for those interested. Workshop applications will be considered until **May 01, 2022**, or until all slots are allocated. We will also entertain requests for workshops to be held in remote or hybrid modes. ## Workshop Proposal Submission Visit the submission link for the workshop proposal form and for more information on requirements and the evaluation process. To submit a workshop proposal, you will need to login to http://conf.research.org. ## Important Deadlines - The deadline for proposal submission for all workshops is **May 01, 2022** - The deadline for paper/abstract submission for all workshops is **September 01, 2022** - The early registration deadline for SPLASH is **TBD**. Before the SPLASH early registration deadline, all workshops must a) send out accept/reject notifications, and b) publish a draft schedule on the SPLASH website. For workshops with proceedings published in the ACM Digital Library, **TBD** is the camera-ready deadline. Therefore, you should plan to notify authors several days before this date, so that they have time for revisions. **TBD** dates will be announced as soon as the SPLASH dates they are dependent on are decided. ## Questions Please [email the workshop co-chairs](mailto:workshops@splashcon.org) with any questions. ## Submission Link https://bit.ly/splash2022w ## Organizing Committee - Mehdi Bagherzadeh, Oakland University, USA - Raffi Khatchadourian, CUNY Hunter College, USA

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Problem with ghc-9.2.2 on Windows
by Ben Franksen 28 Apr '22

28 Apr '22

Hi everyone I have a strange problem with ghc-9.2.2 on Windows. I recently updated the cabal file for darcs to allow building with ghc-9.2, which required only a few minor changes. But when I ran the tests using our github CI I noticed two regressions vs. ghc-9.0.2 on Windows. It turned out that both tests (shell scripts) try to run the darcs executable under test with a restricted PATH environment variable; the idea is to test what happens if darcs tries to run some external program which cannot be found in the PATH. The problem is that executing darcs under these circumstances fails immediately without any error message. In fact it seems to fail *before the main procedure is executed*. I tested this by printing some text to stderr in main before doing anything else and the text is not printed. The error cannot be reproduced with a simple example program, which seems to indicate that the problem may be caused by a library. But I am not aware of any way a library can influence code that is executed before main. Any kind of input on how to diagnose this problem further would be appreciated. I this were on Linux I'd use strace to find out if anything is trying to run an external program before main but this happens on Windows only and the only access I have to a Windows machine to run tests on is via the github CI. BTW, using `cabal freeze` I found these differences in library versions between the ghc-9.0 and ghc-9.2 builds. If I am not mistaken they are all "boot" libraries i.e. ones that come with ghc. ben@home[1]:.../darcs/screened>diff cabal.project.freeze-ghc-9.0 cabal.project.freeze-ghc-9.2 2c2 < constraints: any.Cabal ==3.4.1.0, --- > constraints: any.Cabal ==3.6.3.0, 25c25 < any.base ==4.15.1.0, --- > any.base ==4.16.1.0, 34c34 < any.binary ==0.8.8.0, --- > any.binary ==0.8.9.0, 37c37 < any.bytestring ==0.10.12.1, --- > any.bytestring ==0.11.3.0, 51c51 < any.containers ==0.6.4.1, --- > any.containers ==0.6.5.1, 61c61 < any.deepseq ==1.4.5.0, --- > any.deepseq ==1.4.6.1, 73c73 < any.filepath ==1.4.2.1, --- > any.filepath ==1.4.2.2, 76,78c76,78 < any.ghc-bignum ==1.1, < any.ghc-boot-th ==9.0.2, < any.ghc-prim ==0.7.0, --- > any.ghc-bignum ==1.2, > any.ghc-boot-th ==9.2.2, > any.ghc-prim ==0.8.0, 81a82 > haskeline +examples +terminfo, 113c114 < any.parsec ==3.1.14.0, --- > any.parsec ==3.1.15.0, 137c138 < any.stm ==2.5.0.0, --- > any.stm ==2.5.0.2, 148c149 < any.template-haskell ==2.17.0.0, --- > any.template-haskell ==2.18.0.0, 163c164 < any.time ==1.9.3, --- > any.time ==1.9.3 || ==1.11.1.1, Cheers Ben -- I would rather have questions that cannot be answered, than answers that cannot be questioned. -- Richard Feynman

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Second CfP: FMBC 2022 - 4th International Workshop on Formal Methods for Blockchains
by Zaynah Dargaye 27 Apr '22

27 Apr '22

FMBC 2022 Second Call for Papers [ Please distribute, apologies for multiple postings. ] ======================================================================== 4th International Workshop on Formal Methods for Blockchains (FMBC) - First Call https://fmbc.gitlab.io/2022 August 11, 2022, Haifa, Israel Co-located with the The Federated Logic Conference 2022 (FLoC 22 -- https://www.floc2022.org/) as a satellite workshop of the 34th International Conference on Computer-Aided Verification (CAV 2022 -- http://i-cav.org/2022/) ----------------------------------------------------------------- Important dates --------------------- Abstract submission: May 3, 2022 Full paper submission: May 10, 2022 Notification: June 15, 2022 Camera-ready: July 13, 2022 Workshop: August 11, 2022 Deadlines are Anywhere on Earth -- https://en.wikipedia.org/wiki/Anywhere_on_Earth. ---------------------- ---------------------- TOPICS OF INTEREST --------------------- Blockchains are decentralized transactional ledgers that rely on cryptographic hash functions for guaranteeing the integrity of the stored data. Participants on the network reach agreement on what valid transactions are through consensus algorithms. Blockchains may also provide support for Smart Contracts. Smart Contracts are scripts of an ad-hoc programming language that are stored in the Blockchain and that run on the network. They can interact with the ledger’s data and update its state. These scripts can express the logic of possibly complex contracts between users of the Blockchain. Thus, Smart Contracts can facilitate the economic activity of Blockchain participants. With the emergence and increasing popularity of cryptocurrencies such as Bitcoin and Ethereum, it is now of utmost importance to have strong guarantees of the behavior of Blockchain software. These guarantees can be brought by using Formal Methods. Indeed, Blockchain software encompasses many topics of computer science where using Formal Methods techniques and tools are relevant: consensus algorithms to ensure the liveness and the security of the data on the chain, programming languages specifically designed to write Smart Contracts, cryptographic protocols, such as zero-knowledge proofs, used to ensure privacy, etc. This workshop is a forum to identify theoretical and practical approaches of formal methods for Blockchain technology. Topics include, but are not limited to: * Formal models of Blockchain applications or concepts * Formal methods for consensus protocols * Formal methods for Blockchain-specific cryptographic primitives or protocols * Design and implementation of Smart Contract languages * Verification of Smart Contracts ---------------------- ---------------------- SUBMISSION --------------------- Submit original manuscripts (not published or considered elsewhere) with a page limit of 12 pages for full papers and Systematization of Knowledge (SoK) papers, 6 pages for short papers, and 2 pages for tool papers (excluding bibliography and short appendix of up to 5 additional pages). Alternatively, you may also submit an extended abstract of up to 3 pages (including a bibliography) summarizing your ongoing work in the area of formal methods and blockchain. Authors of selected extended abstracts are invited to give a short lightning talk. -------------------- -------------------- PROCEEDINGS ------------------- All submissions will be peer-reviewed by at least three members of the program committee for quality and relevance. Accepted regular papers (full and short papers) will be included in the workshop proceedings. , published as a volume of the OpenAccess Series in Informatics (OASIcs <https://www.dagstuhl.de/en/publications/oasics/>) by Dagstuhl. ---------------------- ---------------------- INVITED SPEAKER --------------------- Massimo Bartoletti, Professor, Università degli Studi di Cagliari, Italy ---------------------- ---------------------- PROGRAM COMMITTEE --------------------- PC CO-CHAIRS * Zaynah Dargaye (Nomadic Labs, France) (zaynah.dargaye(a)nomadic-labs.com) * Clara Schneidewind, (MPI-SP, Germany) (clara.schneidewind(a)mpi-sp.org) PC MEMBERS Wolfgang Ahrendt (Chalmers University of Technology, Sweden) Leonardo Alt (Ethereum Foundation, Germany) Lacramioara Astefanoaei (Nomadic Labs, France) Roberto Blanco (MPI-SP, Germany) Joachim Breitner (Germany) Achim Brucker (University of Exeter, UK) Ethan Cecchetti (University of Maryland, USA) Manuel Chakravarty (IOHK & Tweag, Netherlands) Jing Chen (Algorand Inc, USA) Jérémie Decouchant (TU Delft, Netherlands) Antonella Del Pozzo (Université Paris-Saclay & CEA & List, France) Dana Drachsler Cohen (Technion, Israel) Cezara Dragoi (INRIA & ENS & CNRS & PSL, France) Ansgar Fehnker (Twente, Netherlands) Dominik Harz (Interlay & Imperial College London, UK) Lars Hupel (INNOQ, Germany) Igor Konnov (Informal Systems, Austria) Paul Laforgue (Nomadic Labs, France) Julian Nagele (Bank of America, USA) Russel O’Connor (Blockstream) Maria Potop-Butucaru (LIP6, France) Albert Rubio (Complutense University of Madrid, Spain) César Sanchez (IMDEA, Spain) Sun Meng (Peking University, China) Simon Thompson (IO Global, UK) Josef Widder (Informal Systems, Austria)

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Shutting down a Yesod/warp application
by Olaf Klinke 27 Apr '22

27 Apr '22

Dear Cafe, this topic has been discussed [1,2] a decade ago. What is the current state of affairs in this matter? It still seems to be addressed neither in yesod nor warp [*]. We have two use cases: (1) A shutdown route that allows admins to cleanly shut down the web application. (2) We want certain exceptions to terminate the application and have the surrounding monitoring (systemd, docker, ...) re-start the application. For (2) we are safe, I think, because the worker threads are forked from the main thread [3] calling warp, so propagating the exceptions up to the top bypasses warp and yesod's very comprehensive exception handlers. But any exception thrown while answering a request (such as (1)) is caught by default. Thanks Olaf [1] https://groups.google.com/g/yesodweb/c/VoenrabRUBQ [2] https://stackoverflow.com/questions/7881327/how-do-i-implement-a-shutdown-c… [3] https://mail.haskell.org/pipermail/haskell-cafe/2022-March/135132.html [*] Warp offers setOnException and setOnExceptionResponse. But does re- throwing certain exceptions from there terminate warp?

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Position of Lecturer or Senior Lecturer in Cybersecurity at University of Sheffield
by Andrei Popescu 26 Apr '22

26 Apr '22

Greetings, The Department of Computer Science at University of Sheffield has an open position of Lecturer or Senior Lecturer in Cybersecurity. Details can be found here: https://www.jobs.ac.uk/job/COY785/lecturer-senior-lecturer-in-cybersecurity Note that "formalisation and proof of system security properties" is listed as a topic of interest. Women are particularly encouraged to apply. All applicants will be given equal consideration. Best wishes, Andrei

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Munich Haskell Meeting, 2022-04-28 @ 19:30
by Leah Neukirchen 26 Apr '22

26 Apr '22

Dear all, This week, our monthly Munich Haskell Meeting will take place again on Thursday, April 28 at Augustiner-Gaststätte Rumpler at 19:30 CEST. For details see here: http://muenchen.haskell.bayern/dates.html If you plan to join, please add yourself to this dudle so we can reserve enough seats! It is OK to add yourself to the dudle anonymously or pseudonymously. https://dudle.inf.tu-dresden.de/haskell-munich-apr-2022/ Everybody is welcome! cu, -- Leah Neukirchen <leah(a)vuxu.org> https://leahneukirchen.org/

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Near Semi Ring problem
by Henry Laxen 23 Apr '22

23 Apr '22

Dear Group, Many years ago I read a fascinating article which I can't seem to find anymore. It was about writing down (in english) the numbers from one to a billion? and being able to retrieve the nth letter. ie: onetwothreefourfive...ninehundredninetymillion....ninetynineonebillion I remember it used near semi rings and automatic differentiation, but no matter how I use those words to search (both google and duckduck) I can't find it. Do any of you have a pointer. I believe the code was written in haskell too. Best wishes, Henry Laxen

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