- Haskell-Cafe - Haskell.org

strange cabal error
by Ben Franksen 18 Mar '21

18 Mar '21

Any idea what I am running into here? ben@home[5]:.../softIOC/home>cabal build Resolving dependencies... TODO: add support for multiple packages in a directory CallStack (from HasCallStack): error, called at ./Distribution/Client/ProjectOrchestration.hs:548:9 in main:Distribution.Client.ProjectOrchestration This appears immediately after I issued a (successful) ben@home[5]:.../softIOC/home>cabal init --minimal --package-name test Cheers Ben -- I would rather have questions that cannot be answered, than answers that cannot be questioned. -- Richard Feynman

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Some Alex beginner questions regarding parsing Java
by Javran Cheng 18 Mar '21

18 Mar '21

Hi Cafe! Firstly, sorry for spamming if you already see this on Stack Overflow, I do feel this is too much for a single SO question. I'm recently playing with Alex + Happy to try parsing Java (for now I'm only working on the lexer / Alex, so whenever you see "parse" below, that means tokenize). My reference is Java SE 15 Spec, the chapter of interest is Chapter 3. Lexical Structure <https://docs.oracle.com/javase/specs/jls/se15/html/jls-3.html> (side note: my timing is a bit interesting as I just realized as of writing this, Java SE 16 spec is out just few days ago, so I might switch to that) and now that I've get my hand dirty a bit, I have few questions and hope if someone can shed some light on them: 1. For now I'm using "monad-bytestring" wrapper for performance, but now I think maybe String-based wrapper is more appropriate, for it allows me to follow 1. and 2. in "3.2. Lexical Translations" properly before passing the input to Alex - namely I can pre-process input stream to (1) do Unicode escaping to turn the raw byte flow into a flow of Chars (2) I can normalize line terminators into just \n. But: 1. Are those two passes (Unicode escape and line terminator normalization) possible within Alex framework? 2. Is there any way that I can stick with a memory-compact string representation? (not sure why Alex doesn't provide any Text-based wrapper, as it did mention in its doc that it internally works on UTF-8 encoded byte sequence) I could probably consider to not use any wrapper, as GHC and Agda did, but that's sort of an undocumented territory so I'm hesitated to do so. 2. The other trouble I have regarding "3.2. Lexical Translations" is the special rules applied to ">"s: "... There is one exception: if lexical translation occurs in a type context (§4.11) ..." - but how in the world am I going to do this? I mean the lexical analysis is not even done how am I going to tell whether it's a type context (and §4.11 is quite long that I won't even try to read it, unless forced)? Maybe I can just tokenize every ">" as an individual operatior, as if ">>", ">>=", ">>>", and ">>>=" don't exist and worry about that later, but that doesn't sound right to me. 3. I realize there's a need for "irrecoverable failure": I have a test case with octal literal "012389", which is supposed to fail, but Alex happily tokenized that into [octal "0123", decimal "89"] - for now my workaround is for every number literal to check whether previous char is a digit and fail if it is indeed so, but I feel this is like ducktaping on a flawed approach and at some point it will fail on some edge cases. an ideal fix IMO would be to have some notion of irrecoverable failure - failing to parse a literal at full should be irrecoverable rather than trying to parse most of it and move on. In addition, as Java spec requires that if a numeric literal doesn't fit in the intended type, it's a compilation error - which can also be encoded as an irrecoverable failure as well. I'm not sure how to do that in Alex though, I can see few ways: 1. encode irrecoverable failure by setting to a special startcode, which does not provide anyway to go back to startcode 0 - so an irrecoverable failure sets that special startcode, and at the start of every action, it checks whether startcode is the special "failure" startcode and fail accordingly 2. this is similar to startcode, but use a wrapper that supports userstate. 3. maybe this is another case that not using a wrapper would give me more control, but I don't have a concrete idea regarding this alternative. Any thoughts on this is appreciated. Thanks! Javran (Fang) Cheng

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Re: [Haskell-cafe] shorter error messages
by Richard Eisenberg 17 Mar '21

17 Mar '21

In the short-term: I'll take option 3. We've already changed some of the datatypes around there, and the new output reflects the new structure. I did poke around a bit (https://gitlab.haskell.org/ghc/ghc/-/issues/19278) asking if anyone relied on the existing structure, and we were told just to update as we saw fit. In the longer-term: Option 1. The JSON feature is, essentially, undesigned. It just happened. There is no real specification or supported story for what tools are likely to consume the data. After this overhaul, it will be easy to imagine arbitrarily structured and informative JSON output, and so I imagine we'll start a conversation with consumers (i.e. IDEs and similar tools) to design an advertised interface. This interface will need to be somewhat unstable in perpetuity, as GHC improves errors, adds new ones, etc. But my hope is that the stated design encompasses this need for change and specifies what will and will not change over time. Maybe even there will be a way to query GHC for its JSON schema? Not sure. An important detail is that the flag for JSON output is -ddump-json, starting with a `d`; this means it's in the "debugging GHC" section of the manual. I hope that changes someday (where "hope" implies that I will actively support efforts at doing so). Richard > On Mar 16, 2021, at 6:01 PM, Sebastiaan Joosten <sjcjoosten(a)gmail.com> wrote: > > Hi Richard, > > this raises a question about the upcoming overhaul: is the JSON dump format following -ddump-json most likely to: > 1. change a lot (complete overhaul is likely and/or feature might disappear - say because all datatypes will be changed and the JSON is just some 'deriving Generic' ToJSON dump with default parameters) > 2. stay the same mostly (if/wherever it changes, it is either a bug or deliberate feature) > 3. change in minor ways (stability is not considered important in the overhaul but there are no reasons to believe this part of the code will be affected much) > ? > > What would your guess be? > > Sebastiaan > > PS: feel free to reply to cafe if that seems fitting – my mails there get rejected (issue on my end) > >> On 16 Mar 2021, at 14:07, Richard Eisenberg <rae(a)richarde.dev> wrote: >> >> There is no "official" way to accommodate this reasonable request. The ideas up-thread are good ones. >> >> I want to pipe in that we're currently going through an internal overhaul of error-message handling that will make such a request much easier to contemplate in the future. This is active work going on right now. So there is hope, possibly for 9.4. Of course, once the internal overhaul is done, we'll need to design any features that actually change the output -- the overhaul just makes it easy to implement such features (which would be very difficult at the moment). >> >> Richard >> >>> On Mar 16, 2021, at 12:56 PM, Jaro Reinders <jaro.reinders(a)gmail.com> wrote: >>> >>> On 16-03-2021 17:40, Tom Smeding wrote: >>>> In any case, the haskell language server just uses GHC internally, so it just shortens the GHC message. But then I believe the same result could be accomplished by some simple text manipulation on GHC's normal output. >>> >>> In fact, you can use -ddump-json to get JSON error messages. I should be easy to convert that to any form you like. >>> >>> But there is no clear specification of that output: >>> https://gitlab.haskell.org/ghc/ghc/-/issues/19278 >>> >>> And I also want to point out that there is a big open issue for better error messages: >>> https://gitlab.haskell.org/ghc/ghc/-/issues/8809 >>> _______________________________________________ >>> Haskell-Cafe mailing list >>> To (un)subscribe, modify options or view archives go to: >>> http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe >>> Only members subscribed via the mailman list are allowed to post. >> >> _______________________________________________ >> Haskell-Cafe mailing list >> To (un)subscribe, modify options or view archives go to: >> http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe >> Only members subscribed via the mailman list are allowed to post. >

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shorter error messages
by Ben Franksen 17 Mar '21

17 Mar '21

Is there a way to tell ghc to print errors, especially type errors in a more concise way? Ideally one or two lines of text? I hate it when I have to scroll several pages of text just to see the next/previous error location. Cheers Ben -- Niemand hat das Recht zu gehorchen. -- Hannah Arendt

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International Conference on Applied Data Science and Intelligence - (ADSI 2021) Prague
by matteo＠confscience.com 17 Mar '21

17 Mar '21

Call for papers ************************************************* International Conference on Applied Data Science and Intelligence - (ADSI 2021) Prague- Czech Republic, October 14-15, 2021 https://confscience.com/adsi/ Submission deadline: April 1, 2021 All papers accepted in ADSI 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 1, 2021 - Acceptance Notification: July 1, 2021 - Final Manuscript Due: September 1, 2021 *************************************************************************** The ADSI 2021 conference will be held in Conjunction with: International Conference on Recent Theories and Applications in Transportation and Mobility (RTATM 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 - Theoretical Models - Spatial and temporal multi-models - Multi-dimensional data - Data acquisition and pre-processing - Data inference - Data Classification and Taxonomy - Data Metrics - New approaches for collaboration and competition - Self-organization, self-healing, fault-tolerance approaches - Spatial reasoning - Context awareness - Intelligent mobility - New approaches to supervised and unsupervised learning - New approaches for security, privacy, trust, and ethics in data science - Real-time data analytics - Multi-Agent Systems for data science - Distributed data analytics - Data authenticity - New theories and approaches for Deep learning - New approaches for Business Intelligence - Fuzzy logic - Decision trees - Support vector machines - Evolutionary computation - Statistical methods - Collaborative filtering - Data engineering - Content mining - Indexing schemes - Information retrieval - Metadata use and management INTELLIGENT DATA PROCESSING AND ANALYTICS - Multi-level data processing - Data analytics optimization - Smart data mining - Machine Learning - Deep Learning - Bio-Inspired Computing - Secure data analytics - Privacy in data analytics - Trust in Big Data - Business intelligence - Visualization Analytics - Intelligence as a Service (IaaS) - Data Science as a Service (DSaaS) - Natural Language Processing - Signal Processing - Simulation and Modeling - Data-Intensive Computing SYSTEMS AND INFRASTRUCTURES - Data storage infrastructure - Data warehouses - Data Query and Indexing Technologies - Software Defined Infrastructures - Software Defined Networks (SDN) - Distributed data systems - Smart grid computing - Intelligent data management - Big Data computing - Smart data networking - Internet of Things - Cyber Physical Systems - Blockchain - Fog and Edge intelligence - Parallel Computing systems - Open Source systems for data science - Embedded intelligence - Embedded data science - In-Memory computing - Intelligent drones - Internet of Drones - Real-time data acquisition systems APPLICATIONS - Intelligent Hazard management - Intelligent data science in healthcare - Intelligent data science in farming - Intelligent data science in Oil and Gas - Smart logistics - Intelligent data science in transportation - Intelligent data science in surveillance - Xtech (Fintech, Agritech, etc.) - Intelligent drones - Digital transformation - Bioinformatics - Marketing - Social Science - E-learning and E-services *************************************************************************** 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=adsi2021) 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/adsi/ *************************************************************************** CONTACT For more information, please send an email to info-adsi(a)confscience.com

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21st Midlands Graduate School in the Foundations of Computing Science: Final Call for Participation
by Andrei Popescu 17 Mar '21

17 Mar '21

FINAL CALL FOR PARTICIPATION 21st Midlands Graduate School in the Foundations of Computing Science MGS 21 12-16 April 2021, virtually https://staffwww.dcs.shef.ac.uk/people/G.Struth/mgs21.html OVERVIEW The annual Midlands Graduate School in the Foundations of Computing Science (MGS) offers an intensive programme of lectures on the mathematical foundations of computing. It addresses first of all PhD students in their first or second year, but is open to anyone interested in its topics, from academia to industry and around the world. The MGS has been run since 1999 and is hosted alternately by the Universities of Birmingham, Leicester, Nottingham and Sheffield. MGS 21 is its 21st incarnation. Information about previous events can be found at the MGS web site http://www.cs.nott.ac.uk/MGS PROGRAMME MGS 21 consists of eight courses, each with four or five hours of lectures and a similar number of exercise sessions. Three courses are introductory; one is given by an invited lecturer. These should be attended by all participants. The remaining more advanced courses should be selected based on interest. MGS 21 aims at a mix of livestreamed and prerecorded lectures and livestreamed exercise sessions, with additional social online events. Invited lectures: Monads and Interactions Tarmo Uustalu, Reykjavik Introductory courses: Category Theory Jacopo Emmenegger, Birmingham Type Theory Thorsten Altenkirch, Nottingham Proof Theory Anupam Das, Birmingham Advanced courses: Homotopy Type Theory Nicolai Kraus, Nottingham Inductive and Coinductive Reasoning with Isabelle/HOL Andrei Popescu, Sheffield Effects and Call-by-Push-Value Paul Levy, Birmingham Formal Modelling and Analysis of Concurrent Systems Mohammad Mousavi, Leicester In addition we are organising a session where participants can briefly present and discuss their own research. A call will be made in March. REGISTRATION Participation at MGS 21 is free of charge, but selective. Requests must be submitted online via https://staffwww.dcs.shef.ac.uk/people/G.Struth/mgs21.html Registration deadline is April 1. ORGANISATION Please direct all queries about MGS 21 to Georg Struth. The Sheffield organisers are Harsh Beohar (H.Beohar(a)sheffield.ac.uk) Andrei Popescu (A.Popescu(a)sheffield.ac.uk) Georg Struth (G.Struth(a)sheffield.ac.uk)

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Can eta-reduction of (\xs -> augment (flip (flip . foldr) xs)) typecheck?
by Viktor Dukhovni 17 Mar '21

17 Mar '21

With both `augment` and `foldr` from GHC.Base: augment :: (forall b. (a -> b -> b) -> b -> b) -> [a] -> [a] augment g = g (:) foldr :: (a -> b -> b) -> b -> [a] -> b ... The function: \xs -> augment (g xs) where g xs c z = foldr c z xs -- pointfree: g == flip (flip . foldr) typechecks (it is in fact just (++)) λ> let g xs c z = foldr c z xs λ> :t \xs -> augment (g xs) \xs -> augment (g xs) :: [a] -> [a] -> [a] Is it possible to explicitly type annotate some `g'` so that the function: (\xs -> (augment . g') xs) :: [a] -> [a] -> [a] is also just (++). That is, basically `g'` is the same as g, but with an explicit type signature that makes the type checker accept the eta-reduced composition? A completely naive attempt, with no type annotations yields: λ> let g xs c z = foldr c z xs λ> :t g g :: [a] -> (a -> b -> b) -> b -> b λ> :t (augment . g) <interactive>:1:2: error: • Couldn't match type: forall b. (a1 -> b -> b) -> b -> b with: (a -> b0 -> b0) -> b0 -> b0 Expected: ((a -> b0 -> b0) -> b0 -> b0) -> [a1] -> [a1] Actual: (forall b. (a1 -> b -> b) -> b -> b) -> [a1] -> [a1] • In the first argument of ‘(.)’, namely ‘augment’ In the expression: augment . g I haven't found any variant type signatures for "g" that make this go. I think this may require impredicative polymorphism, and so can't be done until perhaps QuickLook lands (don't know whether that'll be enough). -- Viktor.

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Final Call for the early round of Papers for the Haskell Symposium 2021
by Hage, J. (Jurriaan) 16 Mar '21

16 Mar '21

Dear all, This is the final call for the early round of papers for the upcoming Haskell Symposium. Please forward to anyone that you believe might be interested. The deadline for this early round is March 19. Note that in May there is still the regular round of submissions. 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 ================== Early and Regular Track ----------------------- The Haskell Symposium uses a two-track submission process so that some papers can gain early feedback. Strong papers submitted to the early track are accepted outright, and the others will be given their reviews and invited to resubmit to the regular track. Papers accepted via the early and regular tracks are considered of equal value and will not be distinguished in the proceedings. Although all papers may be submitted to the early track, authors of functional pearls and experience reports are particularly encouraged to use this mechanism. The success of these papers depends heavily on the way they are presented, and submitting early will give the program committee a chance to provide feedback and help draw out the key ideas. 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 --------- Early track: Submission deadline: 19 March 2021 (Fri) Notification: 23 April 2021 (Fri) 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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Re: [Haskell-cafe] Future of package cryptonite
by Kazu Yamamoto 16 Mar '21

16 Mar '21

Hi Ximin, Cc: haskell-cafe According to the mail archive[1], your messages are not delivered to haskell-cafe. So, I'm citing your response below. [1] https://mail.haskell.org/pipermail/haskell-cafe/2021-March/ --Kazu From: Ximin Luo <infinity0(a)pwned.gg> Subject: Re: [Haskell-cafe] Future of package cryptonite > Sven Panne: >> Am Mo., 15. März 2021 um 01:17 Uhr schrieb Kazu Yamamoto <kazu(a)iij.ad.jp <mailto:kazu@iij.ad.jp>>: >> >> We should also take care of "memory", "foundation" and "basement". >> No action is taken for over a month to >> https://github.com/haskell-foundation/foundation/pull/549 <https://github.com/haskell-foundation/foundation/pull/549> >> >> >> Somehow I'm getting more and more allergic to all these hasty unwarranted "I want to take over package XY" requests. The last release of cryptonite was less than 7 weeks ago, a PR for foundation was not merged within 5 weeks, etc. etc. For god's sake: If you are in such a hurry, just fork locally! Or even better: Give the maintainers a huge pile of $$$, most of them are doing their stuff in their spare time, so you can't expect SLAs where you would have to spend 5 digit sums as a company. Or you can fork visibly on e.g. GitHub under a different package name and let other people decide which variant to take. >> > > The cryptonite bugfix release in January is the *only* activity on the package for many months. As I understand from Kazu, Vincent has personally decided to quit, he just has not publicly announced it (nor made any other communications). > > So this bugfix release seems more of a "I guess I should really do the minimum to stop possible harm", rather than performing expected maintainer duties & making progress on the overall Haskell ecosystem. > >> "Taking over" a package can almost be seen as robbery from the point of view of the original author, and it is actively discouraging people to make their code Open Source. We should be much, much more sensitive in the Haskell community, I haven't seen such things in other language ecosystems. >> > > Haskell as an ecosystem is much smaller than other language ecosystems, and maintainers of key libraries like cryptonite going AWOL is unfortunately more common. Given that, it is expected to see more requests like this. > > Implicit in all of these requests is that, if the original maintainer restarts their normal maintainer activities, they can immediately re-exercise their maintainership activities and previous access. > > Package namespaces are a shared resource and its consequences affect everyone, and so "ownership" is not as simple as "who got it first". That is why we have a package takeover process in the first place. [1] One extreme case outside of Haskell would be the left-pad npm example. Nobody is taking away copyrights, licenses, or source code away from anyone; nobody has the power to do that. > > [1] https://wiki.haskell.org/Taking_over_a_package > >> Having said that, I think that a few projects are blocked by stack issues before they can support GHC 9.0. It would be great if things would be released more in lock-step, I dream of a world where a new GHC comes out in sync with cabal, stack, Stackage, Haskell language server etc. all supporting the new compiler. Other language ecosystems are lightyears ahead regarding this... :-/ >> >> Cheers, >> S. > > -- > GPG: ed25519/56034877E1F87C35 > https://github.com/infinity0/pubkeys.git

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SML vs Haskell types
by Galaxy Being 16 Mar '21

16 Mar '21

Hello, This is my first post here, and it's an odd one, I'll admit. Basically, I'm trying to translate the material in *The Little MLer *to Haskell, the TLMLer being an excellent types workout. So in SML I have this datatype 'a shish = Bottom of 'a | Onion of 'a shish | Lamb of 'a shish | Tomato of 'a shish and this datatype rod = Dagger | Fork | Sword and then this SML function fun is_veggie (Bottom (x)) = true | is_veggie (Onion (x)) = is_veggie (x) | is_veggie (Lamb (x)) = false | is_veggie (Tomato (x)) = is_veggie (x) which has no problem handling tis is_veggie (Onion(Tomato(Bottom(Dagger)))) Now, in Haskell I've translated this (with minor alterations) to data Shish a = Holder a | Onion a (Shish a) | Lamb a (Shish a) | Tomato a (Shish a) data Rod = Dagger | Fork | Sword However, in Haskell these two expressions are different things entirely meal4 = Tomato Dagger (Onion Fork (Lamb Spear (Holder Fork))) meal5 = (Tomato (Onion (Lamb (Holder Fork)))) Here's my attempt at handling meal4 with a Haskell isVeggie isVeggie (Holder (sh)) = True isVeggie (Onion sh (sk)) = isVeggie sk isVeggie (Tomato sh (sk)) = isVeggie sk isVeggie (Lamb sh (sk)) = False This works for meal4, but not for meal5. And yet in the SML world their is_veggie handles (Onion(Tomato(Bottom(Dagger)))) just fine. TLMLer says Onion (Tomato (Bottom (Dagger))) belongs to the type rod shish, while in Haskell Onion (Tomato (Holder (Dagger))) is a bizarre nested beast due to the fact that the data constructor variable of Onion is Tomato (Holder (Dagger)) etc. etc. Can a single Haskell version of isVeggie handle both meal4 and meal5? No? I thought so. But then how would a separate Haskell version of isVeggie handle meal5 -- or is it just too weird? Also, but not critical, how could the Haskell isVeggie be done with guards, i.e., just like a consed list is matched on (x:xs) in the recursion case? I can see that 1:2:3:[] and Onion (Tomato (Bottom (Dagger))) are both conses, but the latter I don't know how to break out into head and tail for a guard case where the individual food items were not mentioned explicitly. IOW, this doesn't work isVeggieKebab :: Shish -> Bool isVeggieKebab Holder (sk) = True isVeggieKebab (shkb (sk)) | (shkb == Onion) || (shkb == Tomato) = isVeggieKebab sk | otherwise = False I'm feeling some doom and gloom about this project. Right at the start this seems to be an insurmountable difference between SML and Haskell type systems. Or I simply don't understand something fundamental here. LB

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