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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/….

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repeat confusion
by Galaxy Being 23 Apr '21

23 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

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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

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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?

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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

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