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Re: [Haskell-cafe] scotty: call for maintainers
by Ryan Scott 14 May '21

14 May '21

Hello, I'm pleased to welcome Daniel Brice and Fumiaki Kinoshita as new scotty maintainers [1]. Thanks for stepping up to take up maintenance of this library! Ryan [1] https://github.com/scotty-web/scotty/issues/274#issuecomment-841181989

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a repo to improve error messages
by Richard Eisenberg 13 May '21

13 May '21

Hi all, Many folks here may be interested in https://discourse.haskell.org/t/proposal-an-issue-tracker-for-better-error-… <https://discourse.haskell.org/t/proposal-an-issue-tracker-for-better-error-…>, a proposal I've just written up for a repo that could be used to improve our error messages. As someone who only occasionally reads Discourse myself, I thought cross-posting here would be helpful. It's probably best to keep the discussion concentrated on Discourse, though. Thanks! Richard

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scotty: call for maintainers
by Ryan Scott 13 May '21

13 May '21

Hello, The scotty web framework [1] is looking for additional maintainers to help keep it a thriving project. The core functionality of scotty has been stable for a while, but there are a number of open issues [2] which concern the design of the framework. Although I have been keeping scotty compiling for a while (as I have code which transitively depends on it), I am not a web developer by trade, and as a result, I don't feel like I have the keenest sense for broad design changes. If you feel like you would be able to step up and fill this role, please let me know! Related issue: https://github.com/scotty-web/scotty/issues/274 [1] https://github.com/scotty-web/scotty [2] https://github.com/scotty-web/scotty/issues

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Second call for the *regular* round of Papers for the Haskell Symposium 2021
by Hage, J. (Jurriaan) 12 May '21

12 May '21

Dear all, First, some * BREAKING NEWS *: Jean-Philippe Bernardy has accepted the invitation to speak at the symposium. He will be talking about Linear Haskell. This is the second call for the *regular* round of papers for the upcoming Haskell Symposium. Please forward to anyone that you believe might be interested. The deadline for this round is May 21. Apologies for receiving multiple copies of this announcement. Best regards, Jurriaan Hage Chair ================================================================================ ACM SIGPLAN CALL FOR SUBMISSIONS Haskell Symposium 2021 ** virtual ** Thu 26 -- Fri 27 August, 2021 http://www.haskell.org/haskell-symposium/2021/ ================================================================================ The ACM SIGPLAN Haskell Symposium 2021 will be co-located with the 2021 International Conference on Functional Programming (ICFP). Due to COVID-19 it will take place **virtually** this year. Like last year, we will be using a lightweight double-blind reviewing process. See further information below. Different from last year is that we offer a new submission category: the tutorial. Details can be found below. The Haskell Symposium presents original research on Haskell, discusses practical experience and future development of the language, and promotes other forms of declarative programming. 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. Regular 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 functional pearls need not necessarily report original academic research results. For example, they may instead report reusable programming idioms, elegant ways to approach a problem, or practical experience that will be useful to other users, implementers, or researchers. The key criterion for such a paper is that it makes a contribution from which other Haskellers can benefit. It is not enough simply to describe a standard solution to a standard programming problem, or report on experience where you used Haskell in the standard way and achieved the result you were expecting. A new submission category for this year's Haskell Symposium is the tutorial. Like with the experience report and the functional pearl, the key criterion for such a paper is that it makes a contribution from which other Haskellers can benefit. What distinguishes a tutorial is that its focus is on explaining an aspect of the Haskell language and/or ecosystem in a way that is generally useful to a Haskell audience. Tutorials for many such topics can be found online; the distinction here is that by writing it up for formal review it will be vetted by experts and formally published. System demonstrations should summarize the system capabilities that would be demonstrated. The proposals will be judged on whether the ensuing session is likely to be important and interesting to the Haskell community at large, whether on grounds academic or industrial, theoretical or practical, technical, social or artistic. Please contact the program chair with any questions about the relevance of a proposal. If your contribution is not a research paper, please mark the title of your experience report, functional pearl, tutorial or system demonstration as such, by supplying a subtitle (Experience Report, Functional Pearl, Tutorial Paper, System Demonstration). Submission Details ================== Formatting ---------- Submitted papers should be in portable document format (PDF), formatted using the ACM SIGPLAN style guidelines. Authors should use the `acmart` format, with the `sigplan` sub-format for ACM proceedings. For details, see: http://www.sigplan.org/Resources/Author/#acmart-format It is recommended to use the `review` option when submitting a paper; this option enables line numbers for easy reference in reviews. Functional pearls, experience reports, tutorials and demo proposals should be labelled clearly as such. Lightweight Double-blind Reviewing ---------------------------------- Haskell Symposium 2021 will use a lightweight double-blind reviewing process. To facilitate this, submitted papers must adhere to two rules: 1. Author names and institutions must be omitted, and 2. References to authors' own related work should be in the third person (e.g., not "We build on our previous work" but rather "We build on the work of "). The purpose of this process is to help the reviewers come to an initial judgment about the paper without bias, not to make it impossible for them to discover the authors if they were to try. Nothing should be done in the name of anonymity that weakens the submission or makes the job of reviewing the paper more difficult (e.g., important background references should not be omitted or anonymized). In addition, authors should feel free to disseminate their ideas or draft versions of their paper as they normally would. For instance, authors may post drafts of their papers on the web or give talks on their research ideas. A reviewer will learn the identity of the author(s) of a paper after a review is submitted. Page Limits ----------- The length of submissions should not exceed the following limits: Regular paper: 12 pages Functional pearl: 12 pages Tutorial: 12 pages Experience report: 6 pages Demo proposal: 2 pages There is no requirement that all pages are used. For example, a functional pearl may be much shorter than 12 pages. In all cases, the list of references is not counted against these page limits. Deadlines --------- Regular track and demos: Submission deadline: 21 May 2021 (Fri) Notification: 23 June 2021 (Wed) Deadlines are valid anywhere on Earth. Submission ---------- Submissions must adhere to SIGPLAN's republication policy (http://sigplan.org/Resources/Policies/Republication/) and authors should be aware of ACM's policies on plagiarism (https://www.acm.org/publications/policies/plagiarism) Program Committee members are allowed to submit papers, but their papers will be held to a higher standard. The paper submission deadline and length limitations are firm. There will be no extensions, and papers violating the length limitations will be summarily rejected. Papers should be submitted through HotCRP at: https://haskell21.hotcrp.com/ Improved versions of a paper may be submitted at any point before the submission deadline using the same web interface. Supplementary material: Authors have the option to attach supplementary material to a submission, on the understanding that reviewers may choose not to look at it. This supplementary material should not be submitted as part of the main document; instead, it should be uploaded as a separate PDF document or tarball. Supplementary material should be uploaded at submission time, not by providing a URL in the paper that points to an external repository. Authors can distinguish between anonymized and non-anonymized supplementary material. Anonymized supplementary material will be visible to reviewers immediately; non-anonymized supplementary material will be revealed to reviewers only after they have submitted their review of the paper and learned the identity of the author(s). Resubmitted Papers: authors who submit a revised version of a paper that has previously been rejected by another conference have the option to attach an annotated copy of the reviews of their previous submission(s), explaining how they have addressed these previous reviews in the present submission. If a reviewer identifies him/herself as a reviewer of this previous submission and wishes to see how his/her comments have been addressed, the conference chair will communicate to this reviewer the annotated copy of his/her previous review. Otherwise, no reviewer will read the annotated copies of the previous reviews. Proceedings =========== Accepted papers will be included in the ACM Digital Library. Their authors will be required to choose one of the following options: - Author retains copyright of the work and grants ACM a non-exclusive permission-to-publish license (and, optionally, licenses the work with a Creative Commons license); - Author retains copyright of the work and grants ACM an exclusive permission-to-publish license; - Author transfers copyright of the work to ACM. For more information, please see ACM Copyright Policy (http://www.acm.org/publications/policies/copyright-policy) and ACM Author Rights (http://authors.acm.org/main.html) Accepted proposals for system demonstrations will be posted on the symposium website but not formally published in the proceedings. Publication date: The official publication date of accepted papers 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. Artifacts ========= Authors of accepted papers are encouraged to make auxiliary material (artifacts like source code, test data, etc.) available with their paper. They can opt to have these artifacts published alongside their paper in the ACM Digital Library (copyright of artifacts remains with the authors). If an accepted paper's artifacts are made permanently available for retrieval in a publicly accessible archival repository like the ACM Digital Library, that paper qualifies for an Artifacts Available badge (https://www.acm.org/publications/policies/artifact-review-badging#available) Applications for such a badge can be made after paper acceptance and will be reviewed by the PC chair. Program Committee ================= Edwin Brady University of St Andrews Koen Claessen Chalmers University of Technology Dominique Devriese Vrije Universiteit Brussel Andy Gill University of Kansas Jurriaan Hage (chair) Universiteit Utrecht Zhenjiang Hu Peking University Ranjit Jhala University of California Patricia Johann Appalachian State University Yukiyoshi Kameyama University of Tsukuba George Karachalias Tweag Ralf Laemmel University of Koblenz-Landau Daan Leijen Microsoft Research Ben Lippmeier Ghost Locomotion Neil Mitchell Facebook Alberto Pardo Universidad de la Republica, Uruguay Matt Roberts Macquarie University Janis Voigtlaender University of Duisburg-Essen Nicolas Wu Imperial College London If you have questions, please contact the chair at: j.hage(a)uu.nl ================================================================================

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[Ann] A new Haskell crypto lib: Z-Botan 0.1.1
by Dong Han 12 May '21

12 May '21

Dear Haskellers: After hundreds of days working. I'm happy to announce that the very first version of [Z-Botan](http://hackage.haskell.org/package/Z-Botan) is published, It's a new crypto lib built around the versatile [botan]( http://botan.randombit.net/) C++ crypto lib. Currently, all crypto stuff exported by Botan FFI is implemented, i.e.: * Random number generators. * Block Cipher and symmetric cipher. * Hash. * MAC. * Key derivation functions. * Password hash. * Constant time multiple precision integers. * Public key creation, import and export. * Public key encryption/decryption * Diffie-Hellman key exchange. * Signature generation & signature verification. * X.509 certificates & X.509 certificate revocation lists. * One time password. * AES Key Wrapping * Format Preserving Encryption. We will continue to polish this work, e.g. build TLS upon it. If you have any crypto usage, please give it a try. as usual, we wish you happy hacking! Cheers~ Dong 2021.05.11

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FMBC 2021 - Final Call for Papers (Deadline extension)
by Bruno Bernardo 10 May '21

10 May '21

[ Please distribute, apologies for multiple postings. ] ======================================================================== 3rd International Workshop on Formal Methods for Blockchains (FMBC) - Final Call https://fmbc.gitlab.io/2021 July 18 or 19 (TBA), 2021, *online* Co-located with the 33nd International Conference on Computer-Aided Verification (CAV 2021) http://i-cav.org/2021/ ------------------------------------------------------------- IMPORTANT DATES -------------------------------- Abstract submission: May 16, 2021 (extended) Paper submission: May 23, 2021 (extended) Notification: June 30, 2021 (extended) Camera-ready: July 14, 2021 (extended) Workshop: July 18 or 19 (TBA), 2021 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 6 pages for short 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 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. Submission link: https://easychair.org/conferences/?conf=fmbc2021 Authors are encouraged to use LaTeX and prepare their submissions according to the instructions and styling guides for OASIcs provided by Dagstuhl. Instructions for authors: https://submission.dagstuhl.de/documentation/authors#oasics At least one author of an accepted paper is expected to present the paper at the workshop as a registered participant. -------------------------------- -------------------------------- 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) by Dagstuhl. -------------------------------- -------------------------------- INVITED SPEAKER -------------------------------- David Dill, Lead Researcher, Blockchain, Novi/Facebook, USA https://research.fb.com/people/dill-david/ -------------------------------- -------------------------------- PROGRAM COMMITTEE -------------------------------- PC CO-CHAIRS * Bruno Bernardo (Nomadic Labs, France) (bruno(a)nomadic-labs.com) * Diego Marmsoler (University of Exeter, UK) (D.Marmsoler(a)exeter.ac.uk) PC MEMBERS * Wolfgang Ahrendt (Chalmers University of Technology, Sweden) * Lacramioara Astefanoei (Nomadic Labs, France) * Massimo Bartoletti (University of Cagliari, Italy) * Joachim Breitner (Dfinity Foundation, Germany) * Achim Brucker (University of Exeter, UK) * Zaynah Dargaye (Nomadic Labs, France) * Jérémie Decouchant (TU Delft, Netherlands) * Dana Drachsler Cohen (Technion, Israel) * Ansgar Fehnker (University of Twente, Netherlands) * Maurice Herlihy (Brown University, USA) * Lars Hupel (INNOQ, Germany) * Florian Kammueller (Middlesex University London, UK) * Igor Konnov (Informal Systems, Austria) * Andreas Lochbihler (Digital Asset, Switzerland) * Simão Melo de Sousa (Universidade da Beira Interior, Portugal) * Karl Palmskog (KTH, Sweden) * Maria Potop-Butucaru (Sorbonne Université, France) * Andreas Rossberg (Dfinity Foundation, Germany) * Albert Rubio (Complutense University of Madrid, Spain) * César Sanchez (Imdea, Spain) * Clara Schneidewind (TU Wien, Austria) * Ilya Sergey (Yale-NUS College/NUS, Singapore) * Mark Staples (CSIRO Data61, Australia) * Meng Sun (Peking University, China) * Simon Thompson (University of Kent, UK) * Josef Widder (Informal Systems, Austria)

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ANN: stack-2.7.1
by Emanuel Borsboom 07 May '21

07 May '21

See https://haskellstack.org/ for installation and upgrade instructions. **Changes since v2.5.1.1:** Behavior changes: * `stack repl` now always warns about GHCi problems with loading multiple packages. It also sets now proper working directory when invoked with one package. See [#5421](https://github.com/commercialhaskell/stack/issues/5421) * `custom-setup` dependencies are now properly initialized for `stack dist`. This makes `explicit-setup-deps` no longer required and that option was removed. See [#4006](https://github.com/commercialhaskell/stack/issues/4006) Other enhancements: * Nix integration now passes `ghcVersion` (in addition to existing `ghc`) to `shell-file` as an identifier that can be looked up in a compiler attribute set. * Nix integration now allows Nix integration if the user is ready in nix-shell. This gets rid of "In Nix shell but reExecL is False" error. * `stack list` is a new command to list package versions in a snapshot. See [#5431](https://github.com/commercialhaskell/stack/pull/5431) * Consider GHC 9.0 a tested compiler and remove warnings. * `custom-preprocessor-extensions` is a new configuration option for allowing stack to be aware of any custom preprocessors you have added to `Setup.hs`. See [#3491](https://github.com/commercialhaskell/stack/issues/3491) * Added `--candidate` flag to `upload` command to upload a package candidate rather than publishing the package. * Error output using `--no-interleaved-output` no longer prepends indentating whitespace. This allows emacs compilation-mode and vim quickfix to locate and track errors. See [#5523](https://github.com/commercialhaskell/stack/pull/5523) Bug fixes: * `stack new` now suppports branches other than `master` as default for GitHub repositories. See [#5422](https://github.com/commercialhaskell/stack/issues/5422) * Ignore all errors from `hi-file-parser`. See [#5445](https://github.com/commercialhaskell/stack/issues/5445) and [#5486](https://github.com/commercialhaskell/stack/issues/5486). * Support basic auth in package-indices. See [#5509](https://github.com/commercialhaskell/stack/issues/5509). * Add support for parsing `.hi`. files from GHC 8.10 and 9.0. See [hi-file-parser#2](https://github.com/commercialhaskell/hi-file-parser/pull/…. **Thanks to all our contributors for this release:** * Aaron Allen * Alexey Kuleshevich * Andreas Källberg * Domen Kožar * Emanuel Borsboom * Felix Yan * Jens Petersen * Kirill Zaborsky * Marcin Tolysz * Matt Audesse * Matthew Wraith * Michael Snoyman * Mike Pilgrem * Simon Michael

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Re: [Haskell-cafe] (Online) Utrecht Summer School on Advanced functional programming
by Olaf Klinke 07 May '21

07 May '21

> The lectures will cover several more advanced topics regarding > programming with types in Haskell, including topics such as: > > * monads and applicative functors; > * lambda calculus; > * generalized algebraic datatypes; > * datatype generic programming > * type families and type-level programming; Even if the schedule is yet to be finalized, a definitive list of topics covered would be nice. Thanks, Olaf

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wai-middleware-validation
by Kenzo Yotsuya 07 May '21

07 May '21

Dear Haskell-Cafe, I've uploaded a new package named wai-middleware-validation to Hackage. This is a WAI middleware to automate the validation of request and response bodies according to the schema defined in OpenAPI. I hope Web API developers using OpenAPI will give it a try. https://hackage.haskell.org/package/wai-middleware-validation https://iij-ii.github.io/wai-middleware-validation/ Thanks, Kenzo Yotsuya

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Repeating type variables in MultiParamTypeClasses instance heads
by Leif-Erik Krüger 07 May '21

07 May '21

Hello Haskell-Cafe, I have a question regarding the rules on type class instances with the MultiParamTypeClasses extension. For single-parameter type classes, there is the restriction that an instance head must have the form `C (T a1 ... an)`, where `C` is a type class, `T` is a data type constructor and `a1 ... an` are distinct type variables ( https://ghc.gitlab.haskell.org/ghc/doc/users_guide/exts/instances.html ). To my knowledge, this restriction ensures the impossibility of potential overlap between instances (except for the case where two instance heads are equivalent, but this case is caught by an error message). This restriction can be lifted with the FlexibleInstances extension, so that instances like `instance C (a, a, b)` and `instance C (a, b, b)` are allowed. As can be seen in this example, FlexibleInstances introduces the potential of overlap with single-parameter type classes. When using MultiParamTypeClasses without FlexibleInstances, the current restrictions on instance heads are similiar to those for single-parameter classes. For each parameter, the instance type must have the form `(T a1 ... an)` with `a1 ... an` being distinct from one another, but type variables can be shared between instance types. Therefore, instances like `instance D [a] [a] [b]` and `instance D [a] [b] [b]` are allowed and do cause potential overlap. If there was the restriction of all type variables in the instance head being different from one another however, I think there would be no potential for overlap, just like with single-parameter type classes. To me, these instances allowed by MultiParamTypeClasses seem similar to the single-parameter class instances that are only possible with FlexibleInstances. And just like FlexibleInstances for single-parameter class instances, they introduce potential overlap, so that the MultiParamTypeClasses extension by itself becomes less "safe" than it otherwise would be. Therefore, it seems reasonable to me to only allow these repeated type variables in instance heads with the FlexibleInstances extension. So, is there a good reason for the design choice of allowing these kinds of overlap without FlexibleInstances? Am I missing something here? Or are the current rules the way they are because of historic reasons? Best regards, Leif-Erik Krüger

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bootstrapping a monad via continuations
by Olaf Klinke 07 May '21

07 May '21

Dear Café, I've been scratching my head over a monad instance. I wonder whether there is a deeper theory behind this. Suppose you have a functor T and you happen to find a special type r such that there is a natural embedding into the continuation monad Cont r. More precisely, if there are natural transformations trans :: forall x. T x -> Cont r x trans' :: forall x. Cont r x -> T x with trans' . trans = id and trans . trans' . return = return trans . trans' . (=<<) (trans . f) = (=<<) (trans . f) then you can define monad operations for T so that trans becomes a monad morphism. Once that T is a monad, one can invoke a theorem from a 1970 paper by Anders Kock and obtain Eilenberg-Moore T-algebra structure on r, and the entire monad structure of T can be recovered from this single T-algebra. Examples of this scheme in the mathematical literature are the Riesz representation theorem, which identifies measures on X with a subset of the space of real functionals (X -> R) -> R. Ultimately, the monad structure of the functor of measures is encoded in the operation that sends a measure on R to its mean. Anders Kock's theorem says: (1) There is a bijecitive correspondence between natural transformations T -> Cont r and functions T r -> r. (2) In particular if T is a monad, (1) restricts to a bijection between monad morphisms and Eilenberg-Moore algebra structures. (Incidentally, this is what underlies the continuation monad transformer: Apply to the structure join :: m (m r) -> m r.) It thus seems that my observation is a kind of converse to part (2), namely if a function T r -> r is an Eilenberg-Moore algebra structure, then T is a monad. The preceding sentence is self-referential though, because the property of being an Eilenberg-Moore algebra depends on monad structure already present. As usual I suspect the answer in one of Edward Kmett's packages, but my Category-Fu is not strong enough to identify the matching concept. Olaf

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Safe Haskell?
by Richard Eisenberg 04 May '21

04 May '21

Hi café, Do you use Safe Haskell? Do you know someone who does? If you do, which of Safe Haskell's guarantees do you rely on? Here, a user of Safe Haskell is someone who relies on any guarantees that Safe Haskell provides, not someone who makes sure to have the right pragmas, etc., in your library so that users can import it Safely. Context: Safe Haskell is not lightweight to support within GHC and the ecosystem. Despite being a formidable research project with a (in my opinion) quite worthwhile goal, it's unclear which of Safe Haskell's purported guarantees are actually guaranteed by GHC. (The lack of unsafeCoerce is not actually guaranteed: https://gitlab.haskell.org/ghc/ghc/-/issues/9562 <https://gitlab.haskell.org/ghc/ghc/-/issues/9562>.) Recent design questions about what should be Safe and what shouldn't be (somehow cannot find the discussion after a few minutes of searching; perhaps fill this in) have been answered only by stabs in the dark. The status quo is causing pain: https://gitlab.haskell.org/ghc/ghc/-/issues/19590 <https://gitlab.haskell.org/ghc/ghc/-/issues/19590>. There are hundreds (maybe thousands) of lines of delicate logic within GHC to support Safe Haskell. These parts of GHC have to be read, understood, and maintained by people with limited time. I thus wonder about deprecating and eventually removing Safe Haskell. I don't have a concrete plan for how to do this yet, but I'm confident we could come up with a migration strategy. The set of people who would win by removing Safe Haskell is easy enough to discover. But this email is intended to discover who would be harmed by doing so. If you know, speak up. Otherwise, I expect I will write up a GHC proposal to remove the feature. Thanks, Richard

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Journal of Functional Programming - Call for PhD Abstracts
by Graham Hutton 04 May '21

04 May '21

Dear all, If you or one of your students recently completed a PhD in the area of functional programming, please submit the dissertation abstract for publication in JFP: simple process, no refereeing, open access, ~200 published to date, deadline 31st May 2021. Please share! Best wishes, Graham Hutton ============================================================ CALL FOR PHD ABSTRACTS Journal of Functional Programming Deadline: 31st May 2021 http://tinyurl.com/jfp-phd-abstracts ============================================================ PREAMBLE: Many students complete PhDs in functional programming each year. As a service to the community, twice per year the Journal of Functional Programming publishes the abstracts from PhD dissertations completed during the previous year. The abstracts are made freely available on the JFP website, i.e. not behind any paywall. They do not require any transfer of copyright, merely a license from the author. A dissertation is eligible for inclusion if parts of it have or could have appeared in JFP, that is, if it is in the general area of functional programming. The abstracts are not reviewed. Please submit dissertation abstracts according to the instructions below. We welcome submissions from both the PhD student and PhD advisor/supervisor although we encourage them to coordinate. ============================================================ SUBMISSION: Please submit the following information to Graham Hutton <graham.hutton(a)nottingham.ac.uk> by 31st May 2021: o Dissertation title: (including any subtitle) o Student: (full name) o Awarding institution: (full name and country) o Date of PhD award: (month and year; depending on the institution, this may be the date of the viva, corrections being approved, graduation ceremony, or otherwise) o Advisor/supervisor: (full names) o Dissertation URL: (please provide a permanently accessible link to the dissertation if you have one, such as to an institutional repository or other public archive; links to personal web pages should be considered a last resort) o Dissertation abstract: (plain text, maximum 350 words; you may use \emph{...} for emphasis, but we prefer no other markup or formatting; if your original abstract exceeds the word limit, please submit an abridged version within the limit) Please do not submit a copy of the dissertation itself, as this is not required. JFP reserves the right to decline to publish abstracts that are not deemed appropriate. ============================================================ PHD ABSTRACT EDITOR: Graham Hutton School of Computer Science University of Nottingham Nottingham NG8 1BB United Kingdom ============================================================ This message and any attachment are intended solely for the addressee and may contain confidential information. If you have received this message in error, please contact the sender and delete the email and attachment. Any views or opinions expressed by the author of this email do not necessarily reflect the views of the University of Nottingham. Email communications with the University of Nottingham may be monitored where permitted by law.

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Promoted data types
by coot＠coot.me 04 May '21

04 May '21

Hello, Currently with `DataKind` extension, Haskell allows to promote terms / types to types / kinds. Currently, one cannot write: ``` data K a where K0 :: forall (x :: a). x -> K a ``` Because `K0` is both a term and a type constructor, and as a term and one cannot represent `x` of kind `a`. Is there a proposal or an issue to allow such declaration and error at use sites of `K0` as a term, rather than at declaration site? Best regards, Marcin Szamotulski

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[Announcement] ZuriHac 2021 (18-20 June) - Registration now open
by Jasper Van der Jeugt 02 May '21

02 May '21

Hey Haskell friends, We are happy to announce that you can now register for ZuriHac 2021. It will take place from Friday 18th to Sunday 20th of June. Like last year, we are holding the event online. While we are sad that we don't yet get to see each other in person, this also allowed ~1000 people to join in 2021, instead of the usual 400-500 in Zurich. We have a couple of exciting things lined up for you this year. Here is a peek preview, but you can always check out https://zurihac.com for up-to-date information. This year, we are honoured to have talks by: - Emily Pillmore - Gabriele Keller - John Hughes - Veronika Romashkina And we have a couple of tutorials and teaching tracks in the works, as well as one more talk. We put a special focus on covering the whole beginner, intermediate, advanced spectrum: - There will be an advanced track held by our friends at Well-Typed. - digitally induced will teach you IHP, a new batteries-included web framework that has been gaining a lot of traction. Check it out at https://ihp.digitallyinduced.com/. - There will be a workshop on Unison, an exciting programming language that shares a lot of Haskell's syntax and semantics. Have a look at https://unisonweb.org/. We are working on more talks and tutorials, so expect further details to be communicated in the coming weeks. Keep an eye on our website! Apart from this, there will be the usual stuff that makes ZuriHac so much fun. There will be projects to hack on with other people, and the possibility to bring your own. There will be plenty of socialising, some impromptu hallway tracks, friendly fellow Haskellers to help you out, and an overall welcoming vibe. A quick note on how the online event works: - The main hub for the event will be on our Discord server. It worked really well for us last year, since it provided a sense of togetherness. It's easy to use, and it has chats, voice, and video. You will get a link when you register. - The talks will be streamed (and recorded) on YouTube. Q&A will be held on Discord. Check out last year's excellent talks: https://youtube.com/playlist?list=PLiU7KJ5_df6aZbNfh_TUJt-6w9N3rYkTX Registration is free and open as of right now: https://zureg.zfoh.ch/register/ Looking forward to seeing you in June! The Zurich Friends of Haskell - https://zfoh.ch

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Free online intro/advanced Haskell courses [YouTube]
by Graham Hutton 01 May '21

01 May '21

Hi all, For the last few months, I've been preparing YouTube videos for the introductory and advanced Haskell courses that I teach to students at the University of Nottingham. The courses have now finished, and the full sets of videos are now available: Intro course: http://www.tinyurl.com/haskell-notts Advanced course: http://www.tinyurl.com/haskell-notts2 There’s also a 25% discount for the textbook on which both of the courses are based, Programming in Haskell: Discount link: http://tinyurl.com/25pct-off Best wishes, Graham — Professor Graham Hutton School of Computer Science University of Nottingham, UK http://www.cs.nott.ac.uk/~pszgmh This message and any attachment are intended solely for the addressee and may contain confidential information. If you have received this message in error, please contact the sender and delete the email and attachment. Any views or opinions expressed by the author of this email do not necessarily reflect the views of the University of Nottingham. Email communications with the University of Nottingham may be monitored where permitted by law.

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ANN: second release candidate for stack-2.7
by Emanuel Borsboom 30 Apr '21

30 Apr '21

You can download binaries for this pre-release from https://github.com/commercialhaskell/stack/releases/tag/rc%2Fv2.7.0.3 Please test it and let us know if you run into any trouble. If all goes well, we expect to release the final version in X weeks. Release notes: * Stack's bindists are now built with GHC 8.10.4, and our `stack.yaml` has moved to lts-17.10. This means Stack can now be built on macOS 11.0 (Big Sur) without ugly workarounds. GHC 8.8 is now the minimum GHC version supported for building Stack itself (but this does not effect _users_ of Stack, which still supports using much older GHC versions). **Changes since v2.7.0.1:** (no changes)

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[ANNOUNCE] Experimental Windows GHC 8.10.5 binary release. Supports Haskell DLLs.
by kyra 29 Apr '21

29 Apr '21

An experimental Windows GHC 8.10.5 64-bit Visual C/Native Windows SDK binary compatible distribution is released. Features: Supports Haskell DLLs. Both static and dynamic compilers are shipped. Uses LLVM tools exclusively, hence linking is blazing fast compared to the stock distro. Is position-independent (can be loaded to any address, not only the lower 2GBs) and generates position-independent code. Based on and targets Microsoft Visual C runtime and native Windows SDK. The "full" variant of distro contains 438 extra prebuilt packages and a set utilities, including not only the mandatory cabal, stack, Happy and Alex, but also linters, formatters, preprocessors, and even beasts like pandoc, haskell-language-server and even Agda compiler. Distribution site: https://awson.github.io/ghc-nw/. Cheers, K. Briantsev (aka awson)

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Munich Virtual Haskell Meeting, 2021-04-29 @ 19:30
by Leah Neukirchen 28 Apr '21

28 Apr '21

Dear all, This week, our monthly Munich Haskell Meeting will take place again tomorrow(!) Thursday, April 29 on Google Meet at 19:30 CEST. **Due to meetup limitations in Bavaria, this meeting will take place online!** For details see here: https://muenchen.haskell.bayern/dates.html A Google Meet link to join the room is provided on the page. Everybody is welcome, especially the Haskellers from Bavaria that do not usually come to our Munich meetings due to travel distance! cu, -- Leah Neukirchen <leah(a)vuxu.org> https://leahneukirchen.org/

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Template Haskell question
by Kai-Oliver Prott 28 Apr '21

28 Apr '21

Dear Cafe, what is the reasoning behind the behavior of the following two Haskell expressions: ghci> :set -XTemplateHaskell ghci> let f x ($([p| x |])) = x in f 1 2 2 ghci> let f ($([p| x |])) x = x in f 1 2 2 I'd have guessed that they should both fail compilation with "Conflicting definitions for ‘x’" like the following expression. ghci> let f x x = x in f 1 2 error: ... Moreover, it seems odd that the "x" on the right side always refers to the rightmost pattern variable "x" (regardless if quoted or not). Cheers, Kai

5 5

Haskell translation and transformation
by Dušan Kolář 27 Apr '21

27 Apr '21

Dear Café, I've tried to make my code more compact and faster in runtime and I tried to use primitive types, e.g. Int#. To omit all influences, I ended with Ackermann function: acker :: Int# -> Int# -> Int# acker 0# n = n +# 1# acker m 0# = acker (m -# 1#) 1# acker m n = acker (m -# 1#) (acker m (n -# 1#)) I was quite surprised, that the result was the same as for function without primitive types when it was compiled with -XStrict option. Both memory and time consumption was the same (small difference under 0.5%). Of course, -O2 option was used. :-) I compared with the same C implementation: int acker(int m, int n) { if (m==0) return n+1; if (n==0) return acker(m-1, 1); return acker(m-1, acker(m,n-1)); } with -O2 option used for gcc, the C code is 7 times faster, for no -O options provided both for ghc and gcc, the C code is also 7 times faster. Thus, no difference. My question is: does the ghc use primitive types automatically when possible? Otherwise, I cannot explain the same times... Or, to my big surprise, using primitives does not save memory and computation time, really? And the other question is about reasoning during translation and code generation, what is the reason the code is so slow? I would guess that forcing primitive types and strict evaluation would produce a code with comparable time to C code... The difference seems to be like the one between compiled code to executable and to low level virtual machine code, which is interpreted then. Versions I used: ghc: 8.10.3 gcc: 10.2.0 Dušan P.S. I definitely don't want to make someone upset with the content, I'm simply wondering... D.

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FMBC 2021 - 3rd Call for Papers (Deadline extensions)
by Bruno Bernardo 27 Apr '21

27 Apr '21

[ Please distribute, apologies for multiple postings. ] ======================================================================== 3rd International Workshop on Formal Methods for Blockchains (FMBC) - Third Call https://fmbc.gitlab.io/2021 July 18 or 19 (TBA), 2021, *online* Co-located with the 33nd International Conference on Computer-Aided Verification (CAV 2021) http://i-cav.org/2021/ ------------------------------------------------------------- IMPORTANT DATES -------------------------------- Abstract submission: May 6, 2021 (extended) Paper submission: May 13, 2021 (extended) Notification: June 24, 2021 (extended) Camera-ready: July 8, 2021 Workshop: July 18 or 19 (TBA), 2021 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 6 pages for short 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 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. Submission link: https://easychair.org/conferences/?conf=fmbc2021 Authors are encouraged to use LaTeX and prepare their submissions according to the instructions and styling guides for OASIcs provided by Dagstuhl. Instructions for authors: https://submission.dagstuhl.de/documentation/authors#oasics At least one author of an accepted paper is expected to present the paper at the workshop as a registered participant. -------------------------------- -------------------------------- 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) by Dagstuhl. -------------------------------- -------------------------------- INVITED SPEAKER -------------------------------- David Dill, Lead Researcher, Blockchain, Novi/Facebook, USA https://research.fb.com/people/dill-david/ -------------------------------- -------------------------------- PROGRAM COMMITTEE -------------------------------- PC CO-CHAIRS * Bruno Bernardo (Nomadic Labs, France) (bruno(a)nomadic-labs.com) * Diego Marmsoler (University of Exeter, UK) (D.Marmsoler(a)exeter.ac.uk) PC MEMBERS * Wolfgang Ahrendt (Chalmers University of Technology, Sweden) * Lacramioara Astefanoei (Nomadic Labs, France) * Massimo Bartoletti (University of Cagliari, Italy) * Joachim Breitner (Dfinity Foundation, Germany) * Achim Brucker (University of Exeter, UK) * Zaynah Dargaye (Nomadic Labs, France) * Jérémie Decouchant (TU Delft, Netherlands) * Dana Drachsler Cohen (Technion, Israel) * Ansgar Fehnker (University of Twente, Netherlands) * Maurice Herlihy (Brown University, USA) * Lars Hupel (INNOQ, Germany) * Florian Kammueller (Middlesex University London, UK) * Igor Konnov (Informal Systems, Austria) * Andreas Lochbihler (Digital Asset, Switzerland) * Simão Melo de Sousa (Universidade da Beira Interior, Portugal) * Karl Palmskog (KTH, Sweden) * Maria Potop-Butucaru (Sorbonne Université, France) * Andreas Rossberg (Dfinity Foundation, Germany) * Albert Rubio (Complutense University of Madrid, Spain) * César Sanchez (Imdea, Spain) * Clara Schneidewind (TU Wien, Austria) * Ilya Sergey (Yale-NUS College/NUS, Singapore) * Mark Staples (CSIRO Data61, Australia) * Meng Sun (Peking University, China) * Simon Thompson (University of Kent, UK) * Josef Widder (Informal Systems, Austria)

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Re: [Haskell-cafe] [Haskell] [ANNOUNCE] GHC 9.2.1-alpha2 released
by Henning Thielemann 26 Apr '21

26 Apr '21

On Thu, 22 Apr 2021, Ben Gamari wrote: > The GHC developers are very happy to announce the availability of the > second alpha release in the 9.2.1 series. Binary distributions, source > distributions, and documentation are available at > > https://downloads.haskell.org/ghc/9.2.1-alpha2 When I try a GHC installed from the Debian tarball I get a permission error on the package.cache because of $ ll /usr/local/ghc-9.2.0.20210422/lib/ghc-9.2.0.20210422/package.conf.d/package.cache -rw------- 1 root root 188641 23. Apr 16:56 /usr/local/ghc-9.2.0.20210422/lib/ghc-9.2.0.20210422/package.conf.d/package.cache I can solve the problem with $ sudo chmod a+r /usr/local/ghc-9.2.0.20210422/lib/ghc-9.2.0.20210422/package.conf.d/package.cache

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Smooth developer experience with Cloud IDE for modern Haskell now
by YueCompl 26 Apr '21

26 Apr '21

Dear Cafe, I'd like to share that I find that, we can have rather smooth developer experience for Haskell, on cloud, now. Gitpod (https://gitpod.io <https://gitpod.io/>) recently supported VSCode in addition to Eclipse Theia, making the UX much more smoother, with proper Gitpod workspace setup, now it's much easier for Haskell beginners, as well as chromeOS and Windows users to painlessly onboard modern Haskell. Github codespaces (https://github.com/features/codespaces <https://github.com/features/codespaces>) is up coming too, there sure will be industry strength cloud infrastructures for serious Haskell development soon. And the setup can be fully automated, a full fledged Cloud IDE for modern Haskell development, is only a click away, see my demo: https://github.com/complyue/GHCiCode#readme <https://github.com/complyue/GHCiCode#readme> I also expect more beginner-friendly tutorials can be written this way, especially for Windows users, they'll be able to touch & feel the mass without going through painful setup procedures. Sincerely, Compl

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WST 2021: deadline extension (9 May, 2021)
by Samir Genaim 25 Apr '21

25 Apr '21

====================================================================== WST 2021 - Call for Papers 17th International Workshop on Termination http://costa.fdi.ucm.es/wst2021 July 16, 2021, Pittsburgh, PA, United States Co-located with CADE-28 **** The workshop will be virtual **** ====================================================================== *[The submission deadline was extended to May 9, 2021].* The Workshop on Termination (WST) traditionally brings together, in an informal setting, researchers interested in all aspects of termination, whether this interest be practical or theoretical, primary or derived. The workshop also provides a ground for cross-fertilization of ideas from the different communities interested in termination (e.g., working on computational mechanisms, programming languages, software engineering, constraint solving, etc.). The friendly atmosphere enables fruitful exchanges leading to joint research and subsequent publications. IMPORTANT DATES: * * submission deadline: May 9, 2021* (extended) * notification: June 6, 2021 * final version due: June 20, 2021 * workshop: July 16, 2021 INVITED SPEAKERS: TBA TOPICS: The 17th International Workshop on Termination welcomes contributions on all aspects of termination. In particular, papers investigating applications of termination (for example in complexity analysis, program analysis and transformation, theorem proving, program correctness, modeling computational systems, etc.) are very welcome. Topics of interest include (but are not limited to): * abstraction methods in termination analysis * certification of termination and complexity proofs * challenging termination problems * comparison and classification of termination methods * complexity analysis in any domain * implementation of termination methods * non-termination analysis and loop detection * normalization and infinitary normalization * operational termination of logic-based systems * ordinal notation and subrecursive hierarchies * SAT, SMT, and constraint solving for (non-)termination analysis * scalability and modularity of termination methods * termination analysis in any domain (lambda calculus, declarative programming, rewriting, transition systems, etc.) * well-founded relations and well-quasi-orders SUBMISSION GUIDELINES: Submissions are short papers/extended abstracts which should not exceed 5 pages. There will be no formal reviewing. In particular, we welcome short versions of recently published articles and papers submitted elsewhere. The program committee checks relevance and provides additional feedback for each submission. The accepted papers will be made available electronically before the workshop. Papers should be submitted electronically via the submission page: https://easychair.org/conferences/?conf=wst2021 Please, use LaTeX and the LIPIcs style file http://drops.dagstuhl.de/styles/lipics/lipics-authors.tgz to prepare your submission. PROGRAM COMMITTEE: * Martin Avanzini - INRIA Sophia, Antipolis * Carsten Fuhs - Birkbeck, U. of London * Samir Genaim (chair) - U. Complutense de Madrid * Jürgen Giesl - RWTH Aachen * Matthias Heizmann - U. of Freiburg * Cynthia Kop - Radboud U. Nijmegen * Salvador Lucas - U. Politècnica de València * Étienne Payet - U. de La Réunion * Albert Rubio - U. Complutense de Madrid * René Thiemann - U. of Innsbruck

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ANN: first release candidate for stack-2.7
by Emanuel Borsboom 24 Apr '21

24 Apr '21

You can download binaries for this pre-release from here: https://github.com/commercialhaskell/stack/releases/tag/rc%2Fv2.7.0.1<https://github.com/commercialhaskell/stack/releases/tag/rc/v2.7.0.1> **Changes since v2.5.1.1:** Behavior changes: * `stack repl` now always warns about GHCi problems with loading multiple packages. It also sets now proper working directory when invoked with one package. See [#5421](https://github.com/commercialhaskell/stack/issues/5421) * `custom-setup` dependencies are now properly initialized for `stack dist`. This makes `explicit-setup-deps` no longer required and that option was removed. See [#4006](https://github.com/commercialhaskell/stack/issues/4006) Other enhancements: * Nix integration now passes `ghcVersion` (in addition to existing `ghc`) to `shell-file` as an identifier that can be looked up in a compiler attribute set. * Nix integration now allows Nix integration if the user is ready in nix-shell. This gets rid of "In Nix shell but reExecL is False" error. * `stack list` is a new command to list package versions in a snapshot. See [#5431](https://github.com/commercialhaskell/stack/pull/5431) * Consider GHC 9.0 a tested compiler and remove warnings. * `custom-preprocessor-extensions` is a new configuration option for allowing stack to be aware of any custom preprocessors you have added to `Setup.hs`. See [#3491](https://github.com/commercialhaskell/stack/issues/3491) * Added `--candidate` flag to `upload` command to upload a package candidate rather than publishing the package. * Error output using `--no-interleaved-output` no longer prepends indentating whitespace. This allows emacs compilation-mode and vim quickfix to locate and track errors. See [#5523](https://github.com/commercialhaskell/stack/pull/5523) Bug fixes: * `stack new` now suppports branches other than `master` as default for GitHub repositories. See [#5422](https://github.com/commercialhaskell/stack/issues/5422) * Ignore all errors from `hi-file-parser`. See [#5445](https://github.com/commercialhaskell/stack/issues/5445) and [#5486](https://github.com/commercialhaskell/stack/issues/5486). * Support basic auth in package-indices. See [#5509](https://github.com/commercialhaskell/stack/issues/5509). * Add support for parsing `.hi`. files from GHC 8.10 and 9.0. See [hi-file-parser#2](https://github.com/commercialhaskell/hi-file-parser/pull/….

1 0

repeat confusion
by Galaxy Being 24 Apr '21

24 Apr '21

I'm in Bird's *Thinking Functionally with Haskell *and he has this code to transpose a matrix based on a list of row lists transpose :: [[a]] -> [[a]] transpose [xs] = [[x] | x <- xs] transpose (xs:xss) = zipWith (:) xs (transpose xss) then he says transpose can be rewritten with this pattern transpose [] = ... what could be the rest of it? The answer he gives is transpose2 :: [[a]] -> [[a]] transpose2 [] = repeat [] transpose2 (xs:xss) = zipWith (:) xs (transpose2 xss) where repeat [] gives an infinite list of repetitions. And, he says, note that transpose [xs] = zipWith (;) xs (repeat []) = [[x] | x <- xs] I suppose I get this last equation, but I don't understand repeat in transpose2. Can someone explain this to me? LB

4 3

First call for the *regular* round of Papers for the Haskell Symposium 2021
by Hage, J. (Jurriaan) 23 Apr '21

23 Apr '21

Dear all, * Please ignore the message I sent a few minutes ago. It had the wrong subject. Sorry for that. * This is the first call for the *regular* round of papers for the upcoming Haskell Symposium. Please forward to anyone that you believe might be interested. The deadline for this round is May 21. Apologies for receiving multiple copies of this announcement. Best regards, Jurriaan Hage Chair ================================================================================ ACM SIGPLAN CALL FOR SUBMISSIONS Haskell Symposium 2021 ** virtual ** Thu 26 -- Fri 27 August, 2021 http://www.haskell.org/haskell-symposium/2021/ ================================================================================ The ACM SIGPLAN Haskell Symposium 2021 will be co-located with the 2021 International Conference on Functional Programming (ICFP). Due to COVID-19 it will take place **virtually** this year. Like last year, we will be using a lightweight double-blind reviewing process. See further information below. Different from last year is that we offer a new submission category: the tutorial. Details can be found below. The Haskell Symposium presents original research on Haskell, discusses practical experience and future development of the language, and promotes other forms of declarative programming. 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. Regular 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 functional pearls need not necessarily report original academic research results. For example, they may instead report reusable programming idioms, elegant ways to approach a problem, or practical experience that will be useful to other users, implementers, or researchers. The key criterion for such a paper is that it makes a contribution from which other Haskellers can benefit. It is not enough simply to describe a standard solution to a standard programming problem, or report on experience where you used Haskell in the standard way and achieved the result you were expecting. A new submission category for this year's Haskell Symposium is the tutorial. Like with the experience report and the functional pearl, the key criterion for such a paper is that it makes a contribution from which other Haskellers can benefit. What distinguishes a tutorial is that its focus is on explaining an aspect of the Haskell language and/or ecosystem in a way that is generally useful to a Haskell audience. Tutorials for many such topics can be found online; the distinction here is that by writing it up for formal review it will be vetted by experts and formally published. System demonstrations should summarize the system capabilities that would be demonstrated. The proposals will be judged on whether the ensuing session is likely to be important and interesting to the Haskell community at large, whether on grounds academic or industrial, theoretical or practical, technical, social or artistic. Please contact the program chair with any questions about the relevance of a proposal. If your contribution is not a research paper, please mark the title of your experience report, functional pearl, tutorial or system demonstration as such, by supplying a subtitle (Experience Report, Functional Pearl, Tutorial Paper, System Demonstration). Submission Details ================== Formatting ---------- Submitted papers should be in portable document format (PDF), formatted using the ACM SIGPLAN style guidelines. Authors should use the `acmart` format, with the `sigplan` sub-format for ACM proceedings. For details, see: http://www.sigplan.org/Resources/Author/#acmart-format It is recommended to use the `review` option when submitting a paper; this option enables line numbers for easy reference in reviews. Functional pearls, experience reports, tutorials and demo proposals should be labelled clearly as such. Lightweight Double-blind Reviewing ---------------------------------- Haskell Symposium 2021 will use a lightweight double-blind reviewing process. To facilitate this, submitted papers must adhere to two rules: 1. Author names and institutions must be omitted, and 2. References to authors' own related work should be in the third person (e.g., not "We build on our previous work" but rather "We build on the work of "). The purpose of this process is to help the reviewers come to an initial judgment about the paper without bias, not to make it impossible for them to discover the authors if they were to try. Nothing should be done in the name of anonymity that weakens the submission or makes the job of reviewing the paper more difficult (e.g., important background references should not be omitted or anonymized). In addition, authors should feel free to disseminate their ideas or draft versions of their paper as they normally would. For instance, authors may post drafts of their papers on the web or give talks on their research ideas. A reviewer will learn the identity of the author(s) of a paper after a review is submitted. Page Limits ----------- The length of submissions should not exceed the following limits: Regular paper: 12 pages Functional pearl: 12 pages Tutorial: 12 pages Experience report: 6 pages Demo proposal: 2 pages There is no requirement that all pages are used. For example, a functional pearl may be much shorter than 12 pages. In all cases, the list of references is not counted against these page limits. Deadlines --------- Regular track and demos: Submission deadline: 21 May 2021 (Fri) Notification: 23 June 2021 (Wed) Deadlines are valid anywhere on Earth. Submission ---------- Submissions must adhere to SIGPLAN's republication policy (http://sigplan.org/Resources/Policies/Republication/) and authors should be aware of ACM's policies on plagiarism (https://www.acm.org/publications/policies/plagiarism) Program Committee members are allowed to submit papers, but their papers will be held to a higher standard. The paper submission deadline and length limitations are firm. There will be no extensions, and papers violating the length limitations will be summarily rejected. Papers should be submitted through HotCRP at: https://haskell21.hotcrp.com/ Improved versions of a paper may be submitted at any point before the submission deadline using the same web interface. Supplementary material: Authors have the option to attach supplementary material to a submission, on the understanding that reviewers may choose not to look at it. This supplementary material should not be submitted as part of the main document; instead, it should be uploaded as a separate PDF document or tarball. Supplementary material should be uploaded at submission time, not by providing a URL in the paper that points to an external repository. Authors can distinguish between anonymized and non-anonymized supplementary material. Anonymized supplementary material will be visible to reviewers immediately; non-anonymized supplementary material will be revealed to reviewers only after they have submitted their review of the paper and learned the identity of the author(s). Resubmitted Papers: authors who submit a revised version of a paper that has previously been rejected by another conference have the option to attach an annotated copy of the reviews of their previous submission(s), explaining how they have addressed these previous reviews in the present submission. If a reviewer identifies him/herself as a reviewer of this previous submission and wishes to see how his/her comments have been addressed, the conference chair will communicate to this reviewer the annotated copy of his/her previous review. Otherwise, no reviewer will read the annotated copies of the previous reviews. Proceedings =========== Accepted papers will be included in the ACM Digital Library. Their authors will be required to choose one of the following options: - Author retains copyright of the work and grants ACM a non-exclusive permission-to-publish license (and, optionally, licenses the work with a Creative Commons license); - Author retains copyright of the work and grants ACM an exclusive permission-to-publish license; - Author transfers copyright of the work to ACM. For more information, please see ACM Copyright Policy (http://www.acm.org/publications/policies/copyright-policy) and ACM Author Rights (http://authors.acm.org/main.html) Accepted proposals for system demonstrations will be posted on the symposium website but not formally published in the proceedings. Publication date: The official publication date of accepted papers 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. Artifacts ========= Authors of accepted papers are encouraged to make auxiliary material (artifacts like source code, test data, etc.) available with their paper. They can opt to have these artifacts published alongside their paper in the ACM Digital Library (copyright of artifacts remains with the authors). If an accepted paper's artifacts are made permanently available for retrieval in a publicly accessible archival repository like the ACM Digital Library, that paper qualifies for an Artifacts Available badge (https://www.acm.org/publications/policies/artifact-review-badging#available) Applications for such a badge can be made after paper acceptance and will be reviewed by the PC chair. Program Committee ================= Edwin Brady University of St Andrews Koen Claessen Chalmers University of Technology Dominique Devriese Vrije Universiteit Brussel Andy Gill University of Kansas Jurriaan Hage (chair) Universiteit Utrecht Zhenjiang Hu Peking University Ranjit Jhala University of California Patricia Johann Appalachian State University Yukiyoshi Kameyama University of Tsukuba George Karachalias Tweag Ralf Laemmel University of Koblenz-Landau Daan Leijen Microsoft Research Ben Lippmeier Ghost Locomotion Neil Mitchell Facebook Alberto Pardo Universidad de la Republica, Uruguay Matt Roberts Macquarie University Janis Voigtlaender University of Duisburg-Essen Nicolas Wu Imperial College London If you have questions, please contact the chair at: j.hage(a)uu.nl ================================================================================

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Final Call for the early round of Papers for the Haskell Symposium 2021
by Hage, J. (Jurriaan) 23 Apr '21

23 Apr '21

Dear all, This is the first call for the *regular* round of papers for the upcoming Haskell Symposium. Please forward to anyone that you believe might be interested. The deadline for this round is May 21. Apologies for receiving multiple copies of this announcement. Best regards, Jurriaan Hage Chair ================================================================================ ACM SIGPLAN CALL FOR SUBMISSIONS Haskell Symposium 2021 ** virtual ** Thu 26 -- Fri 27 August, 2021 http://www.haskell.org/haskell-symposium/2021/ ================================================================================ The ACM SIGPLAN Haskell Symposium 2021 will be co-located with the 2021 International Conference on Functional Programming (ICFP). Due to COVID-19 it will take place **virtually** this year. Like last year, we will be using a lightweight double-blind reviewing process. See further information below. Different from last year is that we offer a new submission category: the tutorial. Details can be found below. The Haskell Symposium presents original research on Haskell, discusses practical experience and future development of the language, and promotes other forms of declarative programming. 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. Regular 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 functional pearls need not necessarily report original academic research results. For example, they may instead report reusable programming idioms, elegant ways to approach a problem, or practical experience that will be useful to other users, implementers, or researchers. The key criterion for such a paper is that it makes a contribution from which other Haskellers can benefit. It is not enough simply to describe a standard solution to a standard programming problem, or report on experience where you used Haskell in the standard way and achieved the result you were expecting. A new submission category for this year's Haskell Symposium is the tutorial. Like with the experience report and the functional pearl, the key criterion for such a paper is that it makes a contribution from which other Haskellers can benefit. What distinguishes a tutorial is that its focus is on explaining an aspect of the Haskell language and/or ecosystem in a way that is generally useful to a Haskell audience. Tutorials for many such topics can be found online; the distinction here is that by writing it up for formal review it will be vetted by experts and formally published. System demonstrations should summarize the system capabilities that would be demonstrated. The proposals will be judged on whether the ensuing session is likely to be important and interesting to the Haskell community at large, whether on grounds academic or industrial, theoretical or practical, technical, social or artistic. Please contact the program chair with any questions about the relevance of a proposal. If your contribution is not a research paper, please mark the title of your experience report, functional pearl, tutorial or system demonstration as such, by supplying a subtitle (Experience Report, Functional Pearl, Tutorial Paper, System Demonstration). Submission Details ================== Formatting ---------- Submitted papers should be in portable document format (PDF), formatted using the ACM SIGPLAN style guidelines. Authors should use the `acmart` format, with the `sigplan` sub-format for ACM proceedings. For details, see: http://www.sigplan.org/Resources/Author/#acmart-format It is recommended to use the `review` option when submitting a paper; this option enables line numbers for easy reference in reviews. Functional pearls, experience reports, tutorials and demo proposals should be labelled clearly as such. Lightweight Double-blind Reviewing ---------------------------------- Haskell Symposium 2021 will use a lightweight double-blind reviewing process. To facilitate this, submitted papers must adhere to two rules: 1. Author names and institutions must be omitted, and 2. References to authors' own related work should be in the third person (e.g., not "We build on our previous work" but rather "We build on the work of "). The purpose of this process is to help the reviewers come to an initial judgment about the paper without bias, not to make it impossible for them to discover the authors if they were to try. Nothing should be done in the name of anonymity that weakens the submission or makes the job of reviewing the paper more difficult (e.g., important background references should not be omitted or anonymized). In addition, authors should feel free to disseminate their ideas or draft versions of their paper as they normally would. For instance, authors may post drafts of their papers on the web or give talks on their research ideas. A reviewer will learn the identity of the author(s) of a paper after a review is submitted. Page Limits ----------- The length of submissions should not exceed the following limits: Regular paper: 12 pages Functional pearl: 12 pages Tutorial: 12 pages Experience report: 6 pages Demo proposal: 2 pages There is no requirement that all pages are used. For example, a functional pearl may be much shorter than 12 pages. In all cases, the list of references is not counted against these page limits. Deadlines --------- Regular track and demos: Submission deadline: 21 May 2021 (Fri) Notification: 23 June 2021 (Wed) Deadlines are valid anywhere on Earth. Submission ---------- Submissions must adhere to SIGPLAN's republication policy (http://sigplan.org/Resources/Policies/Republication/) and authors should be aware of ACM's policies on plagiarism (https://www.acm.org/publications/policies/plagiarism) Program Committee members are allowed to submit papers, but their papers will be held to a higher standard. The paper submission deadline and length limitations are firm. There will be no extensions, and papers violating the length limitations will be summarily rejected. Papers should be submitted through HotCRP at: https://haskell21.hotcrp.com/ Improved versions of a paper may be submitted at any point before the submission deadline using the same web interface. Supplementary material: Authors have the option to attach supplementary material to a submission, on the understanding that reviewers may choose not to look at it. This supplementary material should not be submitted as part of the main document; instead, it should be uploaded as a separate PDF document or tarball. Supplementary material should be uploaded at submission time, not by providing a URL in the paper that points to an external repository. Authors can distinguish between anonymized and non-anonymized supplementary material. Anonymized supplementary material will be visible to reviewers immediately; non-anonymized supplementary material will be revealed to reviewers only after they have submitted their review of the paper and learned the identity of the author(s). Resubmitted Papers: authors who submit a revised version of a paper that has previously been rejected by another conference have the option to attach an annotated copy of the reviews of their previous submission(s), explaining how they have addressed these previous reviews in the present submission. If a reviewer identifies him/herself as a reviewer of this previous submission and wishes to see how his/her comments have been addressed, the conference chair will communicate to this reviewer the annotated copy of his/her previous review. Otherwise, no reviewer will read the annotated copies of the previous reviews. Proceedings =========== Accepted papers will be included in the ACM Digital Library. Their authors will be required to choose one of the following options: - Author retains copyright of the work and grants ACM a non-exclusive permission-to-publish license (and, optionally, licenses the work with a Creative Commons license); - Author retains copyright of the work and grants ACM an exclusive permission-to-publish license; - Author transfers copyright of the work to ACM. For more information, please see ACM Copyright Policy (http://www.acm.org/publications/policies/copyright-policy) and ACM Author Rights (http://authors.acm.org/main.html) Accepted proposals for system demonstrations will be posted on the symposium website but not formally published in the proceedings. Publication date: The official publication date of accepted papers 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. Artifacts ========= Authors of accepted papers are encouraged to make auxiliary material (artifacts like source code, test data, etc.) available with their paper. They can opt to have these artifacts published alongside their paper in the ACM Digital Library (copyright of artifacts remains with the authors). If an accepted paper's artifacts are made permanently available for retrieval in a publicly accessible archival repository like the ACM Digital Library, that paper qualifies for an Artifacts Available badge (https://www.acm.org/publications/policies/artifact-review-badging#available) Applications for such a badge can be made after paper acceptance and will be reviewed by the PC chair. Program Committee ================= Edwin Brady University of St Andrews Koen Claessen Chalmers University of Technology Dominique Devriese Vrije Universiteit Brussel Andy Gill University of Kansas Jurriaan Hage (chair) Universiteit Utrecht Zhenjiang Hu Peking University Ranjit Jhala University of California Patricia Johann Appalachian State University Yukiyoshi Kameyama University of Tsukuba George Karachalias Tweag Ralf Laemmel University of Koblenz-Landau Daan Leijen Microsoft Research Ben Lippmeier Ghost Locomotion Neil Mitchell Facebook Alberto Pardo Universidad de la Republica, Uruguay Matt Roberts Macquarie University Janis Voigtlaender University of Duisburg-Essen Nicolas Wu Imperial College London If you have questions, please contact the chair at: j.hage(a)uu.nl ================================================================================

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Richard Eisenberg inspired dependent type hacking and some questions
by Clinton Mead 21 Apr '21

21 Apr '21

My apologies for the (kind of) cross post, I originally put a similar question on the Haskell <https://www.reddit.com/r/haskell/comments/mv6m5s/hacking_richard_eisenbergs…> Reddit <https://www.reddit.com/r/haskell/comments/mv6m5s/hacking_richard_eisenbergs…> I'm never sure the best place to post these sorts of things. Inspired by some of the code <https://github.com/goldfirere/video-resources/tree/main/2021-04-20-vectors> from one of Richard Eisenberg's weekly videos <https://www.youtube.com/watch?v=WHeBxSBY0fc> (which I always eagerly await!) I made some adjustments to his code here <https://gist.github.com/clintonmead/dc6233afb14cb04a3e1ae2b44bd0bf08>. Basically the attempt is to be able to deal with compile time known length lists and runtime only known length lists as uniformly as possible, as the logic is the same in both cases. In addition, allowing us to do things like `safeHead (x : xs)` regardless whether we know the length of `xs` at runtime or compile time, because it should never fail. My attempt makes things a bit messier, adding an extra constructor in the runtime case, and then naturally this means all the functions have to be extended to specifically pattern matched on this constructor. I'm trying to wrap my head around dependent types, and I did buy the ebook version of "Type-Driven Development in Idris", but I've never used Idris before so perhaps I'm having some trouble making these examples more concrete. The vague idea I've seemed to have heard is that dependent types blurs the distinction between "values" and "types", so in Idris my thought was as a result we get rid of this messy hacky distinction between the two that's required in Haskell. Can we actually do this and how? And indeed, can we do this in Haskell as well? Does the current GHC type system give us tools to allow what I've designed without bloating all the functions by having to deal with this extra constructor match? Thanks, Clinton

2 2

IntelliJ Haskell plugins?
by Gregory Guthrie 21 Apr '21

21 Apr '21

Does anyone have experience with and a recommendation for the best Haskell for the IntelliJ IDE?

2 3

GLR parser for Haskell?
by Benjamin Redelings 20 Apr '21

20 Apr '21

Hi, I've been looking at the Haskell parser in ghc/compiler/GHC/Parser.y. It relies on post-processing pretty heavily, both to determine the type of parsed expressions (i.e. is "(x,y)" a pattern or expression?) and to reject invalid syntax (i.e. field declarations are parsed as a type, but this is rejected during postprocessing I think, except in constructor declarations). This makes the grammar rather hard to read. To quote [1]: > Insteadof describingthe languageto be parsed,thegrammardescribes > theprocessused to parseit; it'smore like a hand-crafted parsing > program,butcrammed into Backus-Naur Form. Does anybody know if there is another version of the parser generator uses grammar rules that are closer to the grammar rules in the 2010 report? Maybe a GLR grammar? Also, I see that Happy is able to generate GLR parsers. I'm curious if GLR parsers aren't being used just because they are slow, or if there is some other reason they are hard to use. I am not an expert on parsing or grammars, so any insight would be appreciated. Thanks! -BenRI [1] https://escholarship.org/uc/item/8559j464

5 6

Bx 2021 - FINAL CALL FOR PAPERS
by Meng Wang 20 Apr '21

20 Apr '21

Dear Haskellers, Lenses is Bx and our own Edward Kmett will be giving the keynote! Please consider submitting. Best regards, Meng Bx 2021 - FINAL CALL FOR PAPERS ********************************************************************************** 9th International Workshop on Bidirectional Transformations (Bx 2021) as part of the STAF conference (June 21, 2021) running virtually, Western Norway University of Applied Sciences, Bergen, Norway http://bx-community.wikidot.com/bx2021:home ********************************************************************************** * Important dates: * Abstract submission: April 27, 2021 * Paper Submission: May 4, 2021 ********************************************************************************** OVERVIEW ========================================= Bidirectional transformations (bx) are a mechanism for maintaining the consistency between two or more related (and heterogeneous) sources of information (i.e., 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 the industry and the academy 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 2021 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. KEYNOTE ========================================= We are happy to announce our keynote speaker: Edward Kmett. 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 CATEGORIES OF SUBMISSIONS ========================================= Five categories of submissions are considered: * 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 * 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 * Experience Report (7-8 pages) - sharing experiences and lessons learned with bx tools/frameworks/languages - how bx is used in (research/industrial/educational) projects * Short Papers (5 pages) - work in progress - small focused contributions - position papers and research perspectives - critical questions and challenges for bx * 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 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 submissions 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 2021 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. Papers must follow the CEUR one column style available at: http://ceur-ws.org/Vol-XXX/CEURART.zip or https://www.overleaf.com/latex/templates/template-for-submissions-to-ceur-w… and must be submitted via EasyChair: https://easychair.org/conferences/?conf=bx2021 Please also ensure that your submission is legible when printed on a black and white printer. In particular, please check that colors remain distinct and font sizes are legible. Submissions not complying with the above guidelines may be excluded from the reviewing process without further notice. IMPORTANT DATES ========================================= Abstract submission: April 27, 2021 Paper submission: May 4, 2021 Author notification: May 25, 2021 Early registration: May 27, 2021 Workshop: June 21, 2021 PROGRAM CO-CHAIRS ========================================= The workshop is co-organized by Meng Wang (University of Bristol, UK) and Leen Lambers (Hasso Plattner Institute at the University of Potsdam, Germany). In case of questions, please contact the PC chairs at bx2021(a)easychair.org . Please find further information w.r.t. the Bx 2021 workshop at: http://bx-community.wikidot.com/bx2021:home and STAF 2021 conference at: https://staf2021.hvl.no/ PROGRAM COMMITTEE ========================================= Ravi Chugh, University of Chicago, USA Anthony Cleve, University of Namur, Belgium Alcino Cunha, University of Minho, Portugal Romina Eramo, University of L'Aquila, Italy Michael Johnson, Macquarie University, Australia Hsiang Shang Ko, Academia Sinica, Taiwan Ralf Lämmel, University of Koblenz-Landau, Germany Kazutaka Matsuda, Tohoku University, Japan Fernando Orejas, Universitat Politècnica de Catalunya, Spain Roly Perera, Alan Turing Institute, UK Perdita Stevens, The University of Edinburgh, UK Tarmo Uustalu, Reykjavik University, Iceland Jens Weber, University of Victoria, Canada Bernhard Westfechtel, University of Bayreuth, Germany ========================================= _____________________________________ Leen Lambers Senior Researcher at System Analysis and Modeling Group https://hpi.de/giese/personen/dr-leen-lambers.html _____________________________________ Hasso-Plattner-Institut für Digital Engineering gGmbH Universität Potsdam Prof.-Dr.-Helmert-Str. 2-3 D-14482 Potsdam, Germany _____________________________________ Amtsgericht Potsdam, HRB 12184 Geschäftsführung: Prof. Dr. Christoph Meinel _____________________________________ _______________________________________________ Bx mailing list Bx(a)inf.ed.ac.uk http://lists.inf.ed.ac.uk/mailman/listinfo/bx

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International Conference on Recent Theories and Applications in Transportation and Mobility - (RTATM 2021) Prague
by matteo＠confscience.com 20 Apr '21

20 Apr '21

Call for papers ************************************************* International Conference on Recent Theories and Applications in Transportation and Mobility - (RTATM 2021) Prague - Czech Republic, October 14-15, 2021 https://confscience.com/rtatm/ All papers accepted in RTATM 2021 will be published in Springer CCIS (Communications in Computer and Information Science). CCIS is abstracted/indexed in Scopus, SCImago, EI-Compendex, Mathematical Reviews, DBLP, Google Scholar, and Thomson Reuters Conference Proceedings Citation (Former ISI Proceedings) *************************************************************************** IMPORTANT DATES: - Paper Submission: April 20, 2021 (extended) - Acceptance Notification: July 1, 2021 - Final Manuscript Due: September 1, 2021 *************************************************************************** The RTATM 2021 conference will be held in Conjunction with: International Conference on Applied Data Science and Intelligence (ADSI 2021) International Conference on Informatics Revolution for Smarter Healthcare (IRSH 2021) *************************************************************************** TOPICS: Authors are invited to submit their original papers to address the topics of the conference, including but not limited to: FUNDAMENTALS AND THEORIES - Modelling and Simulation Algorithms - Vehicular Wireless Medium Access Control - V2X communications - Routings and Protocols for Connected Vehicles - Mobility Models and Architectures - Distribution Strategies - Traffic Incident Management Systems - Bio-Inspired Approaches - Optimization and Collaboration - Automatic Control in Vehicular Networks - Energy-aware Connected Mobility - Programming Languages - Sustainable Transportation - Multimodal Transportation Networks and Systems - Systemsb Integration - Driver Behavior Models and Simulation - Human Factors and Travel Behaviour - Green Mobility - Regulations and Bylaws for Intelligent - Transportation and Mobility SMART TRANSPORTATION AND LOGISTICS - Mobility Management - Connected Vehicles - VANETs - Predictive Logistics - Spatio-Temporal Event Tracking - Decision Support Systems - Emergency Management - Logistics and E-Commerce - Supply Chain Design and Execution - Supply Chain Management - Advanced Planning Systems - Fleet Management - Multi-Agent Systems - Machine Learning for Smart Logistics - Intelligent Infrastructures - Real-time Analysis of Comprehensive Supply Chain Data - Smart Synchronization of Logistics Processes - New Approaches for Cost Transparency - Big Data for Smart Logistics - Logistics 4.0 - Mobile Networks - Next-Generation Smart Logistics - Performance Management Approaches - Tests and Deployment - Software Defined Networks - Smart Freight Management - Smart Shipment Management - Smart Warehousing - Smart Inventory management DATA AND SERVICES - Real-Time transportation Data Acquisition - Event Detection and Monitoring - Data Warehouses for connected mobility - Data mining and Data analytics - Data Worthiness in Connected Vehicles - Data Trustworthiness for effective transportation and mobility - Road Traffic Data Analytics - Structured and Unstructured Data for Connected Mobility - Volunteered Geographic Information (VGI) - Data Representation for Connected Mobility - Transportation Data Mining - Transportation and mobility Data Visualization - Cognitive and Context-aware Intelligence - Transportation Decision Support Systems - Mobility as a Service (MaaS) - Intelligent Transportation Services - Smart Mobility Services - Big Data and Vehicle Analytics - Massive Data Management - Collective and connected Intelligence - Next Generation Services - Driver Behaviour Analysis - Geo-Spatial Services - Service-Oriented Architecture (SOA) - Web and Mobile Services SAFETY, SECURITY, AND HAZARD MANAGEMENT - Security Issues in Vehicular Communications - Safety Applications of Connected Vehicles - Weather-related Safety solutions - V2V, V2I and I2V Road Safety Applications - Connected Mobility for Hazard Management - Risk Management - Road Traffic Crashes Analytics - Traffic Jam Prediction - Resource Allocation for Hazard Management - Trust and Privacy Issues in Logistics - Management of Exceptional Events - New approaches to Networking Security for Transportation Applications - Failure modes, human factors, software safety - Automated Failure Analysis - Performance and Human Error Analysis - Design and Reliability of Control Systems - Dispersion Modelling Software - Quantification of Risk *************************************************************************** OUTSTANDING PAPERS: Based on the peer review scores as well as the presentations at the conference, the authors of outstanding papers will be invited to extend their works for a potential publication in journals special issues with high impact factors. *************************************************************************** PAPER SUBMISSION: Papers must be submitted electronically as PDF files via easychair (https://easychair.org/conferences/?conf=rtatm2021) All papers will be peer reviewed. Length of Full papers: 12-15 pages long (written in the LNCS/CCIS one-column page format, 400 words per page) Length of Short papers: less than 12 pages For more information, please refer to the conference website: https://confscience.com/rtatm/ *************************************************************************** CONTACT For more information, please send an email to info-rtatm(a)confscience.com

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Trick to have existential type work in this case?
by YueCompl 19 Apr '21

19 Apr '21

Dear Cafe, I believe there should exist some trick that I haven't learned, to have this compile: module PoC.Existential where import Data.Dynamic import qualified Data.Vector.Storable as VS import Foreign import Prelude -- * Necessary artifacts data Series a = Series { seriesLen :: IO Int, readSeries :: Int -> IO a } data SomeArray = forall a. (Typeable a, VS.Storable a) => SomeArray { arrayCap :: Int, arrayPtr :: ForeignPtr a } class ManagedArray t where arrayAtTheMoment :: t -> IO SomeArray data SomeManagedArray = forall t. (Typeable t, ManagedArray t) => SomeManagedArray t In following, I can confirm it works with the nested `do` block flattened (as shown later), but I really need it in the more complex real case, so please bear with me. -- * Things not working managedArrayAsSeries :: SomeManagedArray -> IO Dynamic managedArrayAsSeries (SomeManagedArray ma) = do vec <- do SomeArray cap fp <- arrayAtTheMoment ma return $ VS.unsafeFromForeignPtr0 fp cap let len = return $ VS.length vec rs i = return $ vec VS.! i return $ toDyn $ Series len rs The error: src/PoC/Existential.hs:36:5: error: • Couldn't match type ‘a’ with ‘a0’ ‘a’ is a rigid type variable bound by a pattern with constructor: SomeArray :: forall a. (Typeable a, Storable a) => Int -> ForeignPtr a -> SomeArray, in a pattern binding in a 'do' block at src/PoC/Existential.hs:35:5-20 Expected type: IO (VS.Vector a0) Actual type: IO (VS.Vector a) • In a stmt of a 'do' block: return $ VS.unsafeFromForeignPtr0 fp cap In a stmt of a 'do' block: vec <- do SomeArray cap fp <- arrayAtTheMoment ma return $ VS.unsafeFromForeignPtr0 fp cap In the expression: do vec <- do SomeArray cap fp <- arrayAtTheMoment ma return $ VS.unsafeFromForeignPtr0 fp cap let len = return $ VS.length vec rs i = return $ vec VS.! i return $ toDyn $ Series len rs • Relevant bindings include fp :: ForeignPtr a (bound at src/PoC/Existential.hs:35:19) | 36 | return $ VS.unsafeFromForeignPtr0 fp cap | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ While these more trivial things work as expected: -- * Things working managedArrayAsSeries' :: SomeManagedArray -> IO Dynamic managedArrayAsSeries' (SomeManagedArray ma) = do SomeArray cap fp <- arrayAtTheMoment ma let vec = VS.unsafeFromForeignPtr0 fp cap let len = return $ VS.length vec rs i = return $ vec VS.! i return $ toDyn $ Series len rs arrayAsSeries :: SomeArray -> Dynamic arrayAsSeries (SomeArray cap fp) = colAsSeries $ SomeColumn $ VS.unsafeFromForeignPtr0 fp cap arrayAsSeries' :: SomeArray -> Dynamic arrayAsSeries' (SomeArray cap fp) = do let vec = VS.unsafeFromForeignPtr0 fp cap len = return $ VS.length vec rs i = return $ vec VS.! i toDyn $ Series len rs data SomeColumn = forall a. (Typeable a, VS.Storable a) => SomeColumn (VS.Vector a) colAsSeries :: SomeColumn -> Dynamic colAsSeries (SomeColumn colVec) = toDyn $ Series len rs where len = return $ VS.length colVec rs i = return $ colVec VS.! i Please teach me the trick! Thanks with regards, Compl

2 2

How to move files?
by ☂Josh Chia (謝任中) 15 Apr '21

15 Apr '21

I'm trying to write to a temp file in /tmp and then move it to another location that may be in /tmp. If I use System.Directory.renameFile and the final location is in another filesystem, I'll get an error "renameFile:renamePath:rename: unsupported operation (Invalid cross-device link)". If I copy to the new location and then remove the temp file, but the new location is also in /tmp, I am doing an unnecessary copy (instead of mv), which is inefficient. I don't know how to detect whether two filepaths are in the same filesystem. What's the best way to move the file if possible but copy-and-delete if necessary? Josh

9 13

[ANN] wai-handler-hal-0.1.0.0 - Wrap a WAI Application to run on AWS Lambda
by Jack Kelly 15 Apr '21

15 Apr '21

I have just pushed an initial release of wai-handler-hal[1] to Hackage. This library lets you run `wai` `Application`s on AWS Lambda, using the proxy integration features of an API Gateway REST API. This allows you to write your APIs using tools like `servant`, test them locally using `warp`, and then build deployment binaries using `hal`. There's an especially nice payoff when you use `servant`: it's very easy to test the entire API locally using `warp`, but then split endpoints into individual Lambda binaries. This means you can assign minimal IAM policies to each Lambda when you deploy to AWS. The library code, an example API, example deployment code (in AWS CDK[2]), and extensive documentation are all available on GitHub[3]; bug reports and pull requests are welcome. Best, -- Jack [1]: https://hackage.haskell.org/package/wai-handler-hal-0.1.0.0 [2]: https://aws.amazon.com/cdk/ [3]: https://github.com/bellroy/wai-handler-hal

1 0

Re: [Haskell-cafe] Haskell function composition commutivity?
by Dominic Steinitz 14 Apr '21

14 Apr '21

I’d recommend *not* reading Categories for the Working Mathematician unless you are a mathematician (lots of background assumed) and even then it’s a bit of a dull read. Dominic Steinitz dominic(a)steinitz.org http://idontgetoutmuch.org Twitter: @idontgetoutmuch > From: Viktor Dukhovni <ietf-dane(a)dukhovni.org> > To: haskell-cafe(a)haskell.org > Subject: Re: [Haskell-cafe] Haskell function composition commutivity? > Message-ID: <YHYPMnJcYzdEolzl(a)straasha.imrryr.org> > Content-Type: text/plain; charset=us-ascii > > On Tue, Apr 13, 2021 at 02:19:46PM -0500, Galaxy Being wrote: > >> Your answers seem to originate outside of normal Haskell tutorials. Where >> can I start with this higher superset theory? > > There's a reason why the tutorials don't cover this, the categorical > foundations of Haskell types are not beginner material. It is perhaps > best to defer going down this rabbit hole until you're more comfortable > with the Haskell generally. > > You could start with: > > https://bartoszmilewski.com/2014/10/28/category-theory-for-programmers-the-… > https://bartoszmilewski.com/2015/04/07/natural-transformations/ > > For the Yoneda Lemma specifically, I'd recommend: > > http://blog.sigfpe.com/2006/11/yoneda-lemma.html > > Parametricity is covered in "Theorems for free": > > https://www2.cs.sfu.ca/CourseCentral/831/burton/Notes/July14/free.pdf > > but it is by no means elementary, though skimming it for the essential > facts and skipping the gory details is not too difficult. > > You could also read "Categories for the Working Mathematician" by > Saunders Mac Lane.

2 1

serialized data structures (Was: Generalized, named, and exportable default declarations)
by Olaf Klinke 14 Apr '21

14 Apr '21

> We have seen a lot of effort of better integrating Text into Haskell > programming. The only purpose of doing so is to replace String by > something more space and time efficient. What would happen if we invest > equally much time into making String as efficient as Text? At ICFP 2019 I > attended a talk about Gibbon: > > https://github.com/iu-parfunc/gibbon > > The idea of the project is to serialize (Haskell's) tree data structures > in memory as much as possible. Wouldn't this enable us to use String > instead of Text, again, maybe even lists instead of Vectors? No more Text > integration efforts, no more external library with GHC-specific manual > optimizations. Unfortunately, the project is still in an early stage. So > far, it only supports strict data structures. > > What if we would not complicate the language and generalize syntactic > sugar for Text, but instead improve data layout for all Haskell types and > eventually make a custom Text type unnecessary? So essentially Gibbon's aim is to make String work like Text under the hood, without me having to worry about it? +1 for that! Probably I should not comment on this, because I know too little about compilers and serialization. But having to expect something like OverloadedStrings for arbitrary type classes, plus which effect import statements have on this, puts extra cognitive load on the programmer. In contrast, the direction taken by Gibbon removes worries, namely: How much memory penalty do I pay by using this easy-to-understand algebraic data type instead of a more low-level compact representation? I love GHC specifically for its ability to perform many optimizations that Icould not have come up with. Indeed the GHC devs should strive to make the default [*] types work better, as this aligns with the mission of the Haskell Foundation to promote and widen adoption of Haskell. Olaf [*] "default" as dictated by the language report.

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Generalized, named, and exportable default declarations (GHC Proposal)
by Eric Seidel 14 Apr '21

14 Apr '21

Hi Cafe, The GHC Steering Committee is considering a proposal that would expand the typeclass defaulting mechanism to support arbitrary (single-parameter) classes, and enable exporting defaulting rules. It's received very little input from the community so far, which is a shame because it's trying to address a common complaint about Haskell's String situation. Under the proposal Data.Text could export a rule defaulting IsString to Text. Client modules would automatically import defaulting rules just like class instances, which would make ambiguous string literals automatically default to Text. Please take a look at the proposal and leave your feedback, even if it's just "Yes, this would make my life meaningfully better" (reaction emoji are great for this level of feedback). Gauging the amount of pain caused by problems like this, and weighing that against the cost of new features, is one of the harder parts of being on the Committee. PR: https://github.com/ghc-proposals/ghc-proposals/pull/409 Rendered: https://github.com/blamario/ghc-proposals/blob/exportable-named-default/pro…

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Haskell function composition commutivity?
by Galaxy Being 14 Apr '21

14 Apr '21

I'm in chapter 4 of Bird's very interesting *Thinking Functionally with Haskell *and he has a problem at the end of the chapter where he lists these equations map f . take n = take n . map f map f . reverse = reverse . map f map f . sort = sort . map f map f . filter p = map fst . filter snd . map (fork (f,p)) filter (p . g) = map (invertg) . filter p . map g reverse . concat = concat . reverse . map reverse filter p . concat = concat . map (filter p) adding this caveat for the 3rd equation iff x <= y <=> f x <= f y and this for the 4th equation fork (f,g) x = (f x, g x) and for the 5th invertg satisfies invertg . g = id My confusion is over the commutative-ness of most of this but only anecdotally. With the particularly dense map f . filter p = map fst . filter snd . map (fork (f,p)) We have > :t (map myF . filter myP) Integral b => [b] -> [b] > :t (map fst . filter snd . map (myFork (myF,myP))) Integral b => [b] -> [b] Is there anything universal to be drawn from these anecdotal examples of seeming commutativity? My breakdown of the third equation shows the same type definition for both sides. Is this a way to find equality? All in all, Bird doesn't indicate that there are any underlying truths, just "almost" commutativity. LB

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Re: [Haskell-cafe] What's the modern way to apply a polymorphic function to a Dynamic value in GHC 8.8 and onwards?
by YueCompl 13 Apr '21

13 Apr '21

Thanks to Vlad and Jaro, your solution of `apD` compiles, I think it should work. But unfortunately my real case is a little different / more complex, a MWE appears like this: ```hs holdEvent :: Dynamic -> Dynamic holdEvent (Dynamic t evs') = withTypeable t $ Dynamic typeRep (hcHoldEvent evs') where hcHoldEvent :: forall a. EventSink a -> IO (TimeSeries a) hcHoldEvent !evs = do !holder <- newIORef Nothing listenEvents evs $ writeIORef holder . Just return $ TimeSeries $ readIORef holder data EventSink a = EventSink { listenEvents :: (a -> IO ()) -> IO (), closeStream :: IO () } instance Functor EventSink where fmap = undefined newtype TimeSeries a = TimeSeries {readTimeSeries :: IO (Maybe a)} instance Functor TimeSeries where fmap = undefined ``` Now I'm clueless how to use the `withTypeable` trick to apply my polymorphic `hcHoldEvent` to `Dynamic`, naively written as in above, the error is: ```log src/PoC/DynPoly.hs:20:49: error: • Couldn't match expected type ‘EventSink a0’ with actual type ‘a’ ‘a’ is a rigid type variable bound by a pattern with constructor: Dynamic :: forall a. base-4.13.0.0:Data.Typeable.Internal.TypeRep a -> a -> Dynamic, in an equation for ‘holdEvent’ at src/PoC/DynPoly.hs:19:12-25 • In the first argument of ‘hcHoldEvent’, namely ‘evs'’ In the second argument of ‘Dynamic’, namely ‘(hcHoldEvent evs')’ In the second argument of ‘($)’, namely ‘Dynamic typeRep (hcHoldEvent evs')’ • Relevant bindings include evs' :: a (bound at src/PoC/DynPoly.hs:19:22) t :: base-4.13.0.0:Data.Typeable.Internal.TypeRep a (bound at src/PoC/DynPoly.hs:19:20) | 20 | withTypeable t $ Dynamic typeRep (hcHoldEvent evs') | ^^^^ ``` Thanks with best regards, Compl > On 2021-04-12, at 22:04, Jaro Reinders <jaro.reinders(a)gmail.com> wrote: > > I have no experience in this area, but this compiles: > > ``` > {-# LANGUAGE RankNTypes, ScopedTypeVariables #-} > import Type.Reflection > import Data.Dynamic > > appD :: forall f. Typeable f => (forall a. a -> f a) -> Dynamic -> Dynamic > appD f (Dynamic rep (x :: a)) = withTypeable rep (toDyn (f x)) > ``` > > Cheers, > > Jaro > On 2021-04-12, at 21:06, Vladislav Zavialov <vladislav(a)serokell.io> wrote: > > Would something like this work for you? > > import Type.Reflection > import Data.Dynamic > > apD :: Typeable f => (forall a. a -> f a) -> Dynamic -> Dynamic > apD f (Dynamic t a) = withTypeable t $ Dynamic typeRep (f a) > > - Vlad > >> On 12 Apr 2021, at 14:34, YueCompl via ghc-devs <ghc-devs(a)haskell.org> wrote: >> >> Dear Cafe and GHC devs, >> >> >> There used to be a "principled way with pattern match on the constructor": >> >> ```hs >> data Dynamic where >> Dynamic :: Typeable a => a -> Dynamic >> >> apD :: Typeable f => (forall a. a -> f a) -> Dynamic -> Dynamic >> apD f (Dynamic a) = Dynamic $ f a >> ``` >> Source: https://www.reddit.com/r/haskell/comments/2kdcca/q_how_to_apply_a_polymorph… >> >> >> But now with GHC 8.8 as in my case, `Dynamic` constructor has changed its signature to: >> >> ```hs >> Dynamic :: forall a. TypeRep a -> a -> Dynamic >> ``` >> >> Which renders the `apD` not working anymore. >> >> >> And it seems missing dependencies now for an older solution Edward KMETT provides: >> >> ```hs >> apD :: forall f. Typeable1 f => (forall a. a -> f a) -> Dynamic -> Dynamic >> apD f a = dynApp df a >> where t = dynTypeRep a >> df = reify (mkFunTy t (typeOf1 (undefined :: f ()) `mkAppTy` t)) $ >> \(_ :: Proxy s) -> toDyn (WithRep f :: WithRep s (() -> f ())) >> ``` >> Source: https://stackoverflow.com/questions/10889682/how-to-apply-a-polymorphic-fun… >> >> >> So, how can I do that nowadays? >> >> Thanks, >> Compl >> >> _______________________________________________ >> ghc-devs mailing list >> ghc-devs(a)haskell.org >> http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs >

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What's the modern way to apply a polymorphic function to a Dynamic value in GHC 8.8 and onwards?
by YueCompl 12 Apr '21

12 Apr '21

Dear Cafe and GHC devs, There used to be a "principled way with pattern match on the constructor": ```hs data Dynamic where Dynamic :: Typeable a => a -> Dynamic apD :: Typeable f => (forall a. a -> f a) -> Dynamic -> Dynamic apD f (Dynamic a) = Dynamic $ f a ``` Source: https://www.reddit.com/r/haskell/comments/2kdcca/q_how_to_apply_a_polymorph… But now with GHC 8.8 as in my case, `Dynamic` constructor has changed its signature to: ```hs Dynamic :: forall a. TypeRep a -> a -> Dynamic ``` Which renders the `apD` not working anymore. And it seems missing dependencies now for an older solution Edward KMETT provides: ```hs apD :: forall f. Typeable1 f => (forall a. a -> f a) -> Dynamic -> Dynamic apD f a = dynApp df a where t = dynTypeRep a df = reify (mkFunTy t (typeOf1 (undefined :: f ()) `mkAppTy` t)) $ \(_ :: Proxy s) -> toDyn (WithRep f :: WithRep s (() -> f ())) ``` Source: https://stackoverflow.com/questions/10889682/how-to-apply-a-polymorphic-fun… So, how can I do that nowadays? Thanks, Compl

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[ANN] tasty-bench-0.2.5: featherlight benchmark framework
by Andrew Lelechenko 11 Apr '21

11 Apr '21

I'm happy to announce a release of tasty-bench-0.2.5. It is a featherlight benchmark framework with API mimicking criterion and gauge. https://github.com/Bodigrim/tasty-bench#readme https://hackage.haskell.org/package/tasty-bench-0.2.5 * It supports GHCs from 7.0 to 9.2 alpha. Running benchmarks on a bleeding edge GHC is important to identify potential performance degradation before a compiler is released. * A build on a clean machine is 16 times faster than criterion and 4 times faster than gauge. A build without dependencies is 6 times faster than criterion and 8 times faster than gauge. One can build benchmarks on CI without wasting excessive resources. * Benchmarks can be written together with tests, and can itself be turned into a performance regression test suite. In fact our benchmarks are just regular tasty tests. * Comparisons between benchmarks are readily available out of the box: no external tools (like criterion-compare or bench-show) are required. One can compare results between runs and between individual benchmarks instead of squinting at absolute numbers. Best regards, Andrew

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Taking over scenegraph
by Pippijn van Steenhoven 10 Apr '21

10 Apr '21

Hi all, I've revived http://hackage.haskell.org/package/scenegraph: https://github.com/homectl/lambdaray/tree/main/scenegraph. I'd like to take over maintenance of that package. I can't reach the original author (email address no longer exists). Also, I'm looking for people who would like to join me in working on it and a 3D rendering pipeline based on GPipe. Currently hanging out in #implicitcad on freenode. Cheers, Pippijn

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[ANN] network-packet-linux 0.1.1.0
by Mads Rolsdorph 10 Apr '21

10 Apr '21

Dear Cafe, The network package [0] provides an extensible API for working with sockets. I'm pleased to announce network-packet-linux [1], a small helper package containing the types needed to use the network package with Linux packet sockets [2]. The documentation [3] provides a short example of using network and network-packet-linux for a simple packet sniffer. Have a great weekend! Mads [0] https://hackage.haskell.org/package/network [1] https://hackage.haskell.org/package/network-packet-linux [2] https://man7.org/linux/man-pages/man7/packet.7.html [3] https://hackage.haskell.org/package/network-packet-linux-0.1.1.0/docs/Netwo…

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FMBC 2021 - 2nd Call for Papers
by Bruno Bernardo 10 Apr '21

10 Apr '21

[ Please distribute, apologies for multiple postings. ] ======================================================================== 3rd International Workshop on Formal Methods for Blockchains (FMBC) - Second Call https://fmbc.gitlab.io/2021 July 18 or 19 (TBA), 2021 Co-located with the 33nd International Conference on Computer-Aided Verification (CAV 2021) http://i-cav.org/2021/ ------------------------------------------------------------- IMPORTANT DATES -------------------------------- Abstract submission: April 22, 2021 Full paper submission: April 29, 2021 Notification: June 10, 2021 Camera-ready: July 8, 2021 Workshop: July 18 or 19 (TBA), 2021 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 6 pages for short 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 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. Submission link: https://easychair.org/conferences/?conf=fmbc2021 Authors are encouraged to use LaTeX and prepare their submissions according to the instructions and styling guides for OASIcs provided by Dagstuhl. Instructions for authors: https://submission.dagstuhl.de/documentation/authors#oasics At least one author of an accepted paper is expected to present the paper at the workshop as a registered participant. -------------------------------- -------------------------------- 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) by Dagstuhl. -------------------------------- -------------------------------- INVITED SPEAKER -------------------------------- David Dill, Lead Researcher, Blockchain, Novi/Facebook, USA https://research.fb.com/people/dill-david/ -------------------------------- -------------------------------- PROGRAM COMMITTEE -------------------------------- PC CO-CHAIRS * Bruno Bernardo (Nomadic Labs, France) (bruno(a)nomadic-labs.com) * Diego Marmsoler (University of Exeter, UK) (D.Marmsoler(a)exeter.ac.uk) PC MEMBERS * Wolfgang Ahrendt (Chalmers University of Technology, Sweden) * Lacramioara Astefanoei (Nomadic Labs, France) * Massimo Bartoletti (University of Cagliari, Italy) * Joachim Breitner (Dfinity Foundation, Germany) * Achim Brucker (University of Exeter, UK) * Zaynah Dargaye (Nomadic Labs, France) * Jérémie Decouchant (TU Delft, Netherlands) * Dana Drachsler Cohen (Technion, Israel) * Ansgar Fehnker (University of Twente, Netherlands) * Maurice Herlihy (Brown University, USA) * Lars Hupel (INNOQ, Germany) * Florian Kammueller (Middlesex University London, UK) * Igor Konnov (Informal Systems, Austria) * Andreas Lochbihler (Digital Asset, Switzerland) * Simão Melo de Sousa (Universidade da Beira Interior, Portugal) * Karl Palmskog (KTH, Sweden) * Maria Potop-Butucaru (Sorbonne Université, France) * Andreas Rossberg (Dfinity Foundation, Germany) * César Sanchez (Imdea, Spain) * Clara Schneidewind (TU Wien, Austria) * Ilya Sergey (Yale-NUS College/NUS, Singapore) * Mark Staples (CSIRO Data61, Australia) * Meng Sun (Peking University, China) * Simon Thompson (University of Kent, UK) * Josef Widder (Informal Systems, Austria)

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ML Family Workshop 2021: first call for short abstracts and presentations
by Jonathan Protzenko 09 Apr '21

09 Apr '21

(tl;dr) The ML family workshop is back, and will be held virtually along with ICFP 2021. The workshop does not have proceedings, making it the perfect venue to run some ideas with the community or present some work in progress within a friendly environment. The PC has a broad expertise and submissions are 3 pages long: when in doubt, just submit! (long version) We are happy to announce that the ML Family Workshop is back for its 2021 edition, which we will be held online on Thursday August 26th, in conjunction with ICFP 2021. The ML family workshop warmly welcomes submission touching on the programming languages traditionally seen as part of the "ML family" (Standard ML, OCaml, F#, CakeML, SML#, Manticore, MetaOCaml, etc.). The scope of the workshop includes all aspects of the design, semantics, theory, application, implementation, and teaching of the members of the ML family. We also encourage presentations from related languages (such as Haskell, Scala, Rust, Nemerle, Links, Koka, F*, Eff, ATS, etc), to exchange experience of further developing ML ideas. ## Submission details Submissions must be at most three pages long; see the full call for papers <https://icfp21.sigplan.org/home/mlfamilyworkshop-2021#Call-for-Presentations> for details. Submission site: https://ml21.hotcrp.com/ ## Important dates Thu, May 27th 2021 (AoE): submission deadline Thu, Jun 17th 2021 (AoE): author notification Thu, Aug 26th: workshop (time slots TBD) ## Program committee Danel Ahman (University of Ljubljana) Robert Atkey (University of Strathclyde) Frédéric Bour (Tarides) Ezgi Çiçek (Facebook London) Youyou Cong (Tokyo Institute of Technology) Richard A. Eisenberg (Tweag I/O) Martin Elsman (University of Copenhagen, Denmark) Ohad Kammar (University of Edinburgh) Naoki Kobayashi (University of Tokyo, Japan) Benoît Montagu (Inria) Jonathan Protzenko (Microsoft Research) (Chair) Kristina Sojakova (INRIA Paris) Don Syme (Microsoft) Matías Toro (University of Chile) Katsuhiro Ueno (Tohoku University)

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haskell text://protocol client?
by Petite Abeille 09 Apr '21

09 Apr '21

Hello, Would you know of any haskell text://protocol clients? Or servers? [1][2][3] Thanks in advance. [1] https://textprotocol.org [2] https://github.com/textprotocol/public [3] https://github.com/textprotocol/publictext

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Haskell Joke of the Year 2020
by Nick Rudnick 09 Apr '21

09 Apr '21

Dear all, recently, I was confronted with a question what the Haskell joke of the year 2020 is – for anybody else, whose attention, like mine, this slipped completely, here it is, since it really is quite a bit funny, Haskellers don't make money… :-/ If anybody knows jokes of the other years, I'd be happy to know those, too! Cheers, and thanks in advance, Nick

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