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ICFP 2023: Last Call for Papers
by ICFP Publicity 14 Feb '23

14 Feb '23

PACMPL Volume 7, Issue ICFP 2023 Call for Papers Accepted papers to be invited for presentation at The 28th ACM SIGPLAN International Conference on Functional Programming Seattle, USA http://icfp23.sigplan.org/ ### Important dates (All dates are in 2023 at 11.59pm anywhere on earth.) Submission deadline: 1 March 2023 (Wednesday) (https://icfp23.hotcrp.com) Author response: 1 May (Monday)--4 May (Thursday) Round 1 notification: 18 May (Thursday) Round 2 notification: 29 June (Thursday) Camera-ready deadline: 20 July (Thursday) Conference: 4 September (Monday)--9 September (Saturday) ### About PACMPL Proceedings of the ACM on Programming Languages (PACMPL <https://pacmpl.acm.org/>) is a Gold Open Access journal publishing research on all aspects of programming languages, from design to implementation and from mathematical formalisms to empirical studies. Each issue of the journal is devoted to a particular subject area within programming languages and will be announced through publicised Calls for Papers, like this one. ### Scope [PACMPL](https://pacmpl.acm.org/) issue ICFP 2023 seeks original papers on the art and science of functional programming. Submissions are invited on all topics from principles to practice, from foundations to features, and from abstraction to application. The scope includes all languages that encourage functional programming, including both purely applicative and imperative languages, as well as languages with objects, concurrency, or parallelism. Topics of interest include (but are not limited to): * Language Design: concurrency, parallelism, and distribution; modularity; components and composition; metaprogramming; macros; pattern matching; type systems; type inference; dependent types; effect types; gradual types; refinement types; session types; interoperability; domain-specific languages; imperative programming; object-oriented programming; logic programming; probabilistic programming; reactive programming; generic programming; bidirectional programming. * Implementation: abstract machines; virtual machines; interpretation; compilation; compile-time and run-time optimisation; garbage collection and memory management; runtime systems; multi-threading; exploiting parallel hardware; interfaces to foreign functions, services, components, or low-level machine resources. * Software-Development Techniques: algorithms and data structures; design patterns; specification; verification; validation; proof assistants; debugging; testing; tracing; profiling; build systems; program synthesis. * Foundations: formal semantics; lambda calculus; program equivalence; rewriting; type theory; logic; category theory; computational effects; continuations; control; state; names and binding; program verification. * Analysis and Transformation: control flow; data flow; abstract interpretation; partial evaluation; program calculation. * Applications: symbolic computing; formal-methods tools; artificial intelligence; systems programming; distributed systems and web programming; hardware design; databases; scientific and numerical computing; graphical user interfaces; graphics and multimedia; GPU programming; scripting; system administration; security. * Education: teaching introductory programming; mathematical proof; algebra. Submissions will be evaluated according to their relevance, correctness, significance, originality, and clarity. Each submission should explain its contributions in both general and technical terms, clearly identifying what has been accomplished, explaining why it is significant, and comparing it with previous work. The technical content should be accessible to a broad audience. PACMPL issue ICFP 2023 also welcomes submissions in two separate categories — Functional Pearls and Experience Reports — that must be marked as such when submitted and that need not report original research results. Detailed guidelines on both categories are given at the end of this call. Submissions from underrepresented groups are encouraged. Authors who require financial support to attend the conference can apply for PAC funding (http://www.sigplan.org/PAC/) The General Chair and PC Chair may not submit papers. PC members (other than the PC Chair) may submit papers. However, SIGPLAN guidelines dictate that they be held to a higher standard: a PC paper can be accepted if after the discussion it has at least one strongly-supportive review and no detractors. Each PC member may be listed as a coauthor on a maximum of three submissions. Please contact the Programme Chair if you have questions or are concerned about the appropriateness of a topic. ### Preparation of submissions *Deadline*: The deadline for submissions is **Wednesday, March 1, 2023**, Anywhere on Earth (<https://www.timeanddate.com/time/zones/aoe>). This deadline will be strictly enforced. *Formatting*: Submissions must be in PDF format, printable in black and white on US Letter sized paper and interpretable by common PDF tools. All submissions must adhere to the "ACM Small" template that is available (in both LaTeX and Word formats) from <https://www.acm.org/publications/authors/submissions>. There is a limit of **25 pages for a full paper or Functional Pearl** and **12 pages for an Experience Report**; in either case, the bibliography and an optional clearly marked appendix will not be counted against these limits. Submissions that exceed the page limits or, for other reasons, do not meet the requirements for formatting, will be summarily rejected. See also PACMPL's Information and Guidelines for Authors at <https://pacmpl.acm.org/authors.cfm>. *Submission*: Submissions will be accepted at <https://icfp23.hotcrp.com/> Improved versions of a paper may be submitted at any point before the submission deadline using the same web interface. *Author Response Period*: Authors will have a 72-hour period, starting at 12pm UTC on *Monday, May 1, 2023*, to read reviews and respond to them. *Appendix and Supplementary Material*: Authors have the option to include a clearly marked appendix and/or to attach supplementary material to a submission, on the understanding that reviewers may choose not to look at such an appendix or supplementary material. Supplementary material may be uploaded as a separate PDF document or tarball. Any supplementary material **must** be uploaded **at submission time**, not by providing a URL in the paper that points to an external repository. Authors are free to upload both anonymised and non-anonymised supplementary material. Anonymised supplementary material will be visible to reviewers immediately; non-anonymised supplementary material (which must be submitted separately) will be revealed to reviewers only after they have submitted their review of the paper and learned the identity of the author(s). *Authorship Policies*: All submissions are expected to comply with the ACM Policies for Authorship that are detailed at <https://www.acm.org/publications/authors/information-for-authors>. *Republication Policies*: Each submission must adhere to SIGPLAN's republication policy, as explained on the web at <http://www.sigplan.org/Resources/Policies/Republication>. *ORCID*: ORCID provides a persistent digital identifier (an ORCID iD) that you own and control, and that distinguishes you from every other researcher: https://orcid.org/. ACM now require an ORCID iD for every author of a paper, not just the corresponding author. So, the author who is filling out the permission form should make sure they have the ORCID iDs for all of their coauthors before filling out the form. Any authors who do not yet have an ORCID iD can go to https://orcid.org/register to have one assigned. ### Review Process This section outlines the two-stage process with lightweight double-blind reviewing that will be used to select papers for PACMPL issue ICFP 2023. **New this year**: ICFP 2023 will have an Associate Chair who will help the PC Chair monitor reviews, solicit external expert reviews for submissions when there is not enough expertise on the committee, and facilitate reviewer discussions. *PACMPL issue ICFP 2023 will employ a two-stage review process.* The first stage in the review process will assess submitted papers using the criteria stated above and will allow for feedback and input on initial reviews through the author response period mentioned previously. As a result of the review process, a set of papers will be conditionally accepted and all other papers will be rejected. Authors will be notified of these decisions on **May 18, 2023**. Authors of conditionally accepted papers will be provided with committee reviews along with a set of mandatory revisions. By June 15, 2023, the authors may provide a second submission. The second and final reviewing phase assesses whether the mandatory revisions have been adequately addressed by the authors and thereby determines the final accept/reject status of the paper. The intent and expectation is that the mandatory revisions can feasibly be addressed within three weeks. The second submission should clearly identify how the mandatory revisions were addressed. To that end, the second submission must be accompanied by a cover letter mapping each mandatory revision request to specific parts of the paper. The cover letter will facilitate a quick second review, allowing for confirmation of final acceptance within two weeks. Conversely, the absence of a cover letter will be grounds for the paper's rejection. *PACMPL issue ICFP 2023 will employ 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 judgement 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 anonymised). In addition, authors should feel free to disseminate their ideas or draft versions of their papers as they normally would. For instance, authors may post drafts of their papers on the web or give talks on their research ideas. ### Information for Authors of Accepted Papers * As a condition of acceptance, final versions of all papers must adhere to the ACM Small format. The page limit for the final versions of papers will be increased by two pages to help authors respond to reviewer comments and mandatory revisions: **27 pages plus bibliography for a regular paper or Functional Pearl, 14 pages plus bibliography for an Experience Report**. * Authors of accepted submissions will be required to agree to one of the three ACM licensing options, one of which is Creative Commons CC-BY publication; this is the option recommended by the PACMPL editorial board. A reasoned argument in favour of this option can be found in the article [Why CC-BY?](https://oaspa.org/why-cc-by/) published by OASPA, the Open Access Scholarly Publishers Association. The other options are copyright transfer to ACM or retaining copyright but granting ACM exclusive publication rights. * PACMPL is a Gold Open Access journal, and authors are encouraged to publish their work under a CC-BY license. Gold Open Access guarantees permanent free online access to the definitive version in the ACM Digital Library, and the recommended CC-BY option also allows anyone to copy and distribute the work with attribution. Gold Open Access has been made possible by generous funding through ACM SIGPLAN, which will cover all open access costs in the event authors cannot. Authors who can cover the costs may do so by paying an Article Processing Charge (APC). PACMPL, SIGPLAN, and ACM Headquarters are committed to exploring routes to making Gold Open Access publication both affordable and sustainable. * ACM Author-Izer is a unique service that enables ACM authors to generate and post links on either their home page or institutional repository for visitors to download the definitive version of their articles from the ACM Digital Library at no charge. Downloads through Author-Izer links are captured in official ACM statistics, improving the accuracy of usage and impact measurements. Consistently linking to the definitive version of an ACM article should reduce user confusion over article versioning. After an article has been published and assigned to the appropriate ACM Author Profile pages, authors should visit <http://www.acm.org/publications/acm-author-izer-service> to learn how to create links for free downloads from the ACM DL. * The official publication date is the date the papers are made available in the ACM Digital Library. This date may be up to *two weeks prior* to the first day of the conference. The official publication date affects the deadline for any patent filings related to published work. * Authors of each accepted submission are invited to attend and be available for the presentation of that paper at the conference. The schedule for presentations will be determined and shared with authors after the full program has been selected. ### Artifact Evaluation Authors of papers that are conditionally accepted in the first phase of the review process will be encouraged (but not required) to submit supporting materials for Artifact Evaluation. These items will then be reviewed by an Artifact Evaluation Committee, separate from the paper Review Committee, whose task is to assess how the artifacts support the work described in the associated paper. Papers that go through the Artifact Evaluation process successfully will receive a seal of approval printed on the papers themselves. Authors of accepted papers will be encouraged to make the supporting materials publicly available upon publication of the papers, for example, by including them as "source materials" in the ACM Digital Library. An additional seal will mark papers whose artifacts are made available, as outlined in the ACM guidelines for artifact badging. Participation in Artifact Evaluation is voluntary and will not influence the final decision regarding paper acceptance. ### Special categories of papers In addition to research papers, PACMPL issue ICFP solicits two kinds of papers that do not require original research contributions: Functional Pearls, which are full papers, and Experience Reports, which are limited to half the length of a full paper. Authors submitting such papers should consider the following guidelines. #### Functional Pearls A Functional Pearl is an elegant essay about something related to functional programming. Examples include, but are not limited to: * a new and thought-provoking way of looking at an old idea * an instructive example of program calculation or proof * a nifty presentation of an old or new data structure * an interesting application of functional programming techniques * a novel use or exposition of functional programming in the classroom While pearls often demonstrate an idea through the development of a short program, there is no requirement or expectation that they do so. Thus, they encompass the notions of theoretical and educational pearls. Functional Pearls are valued as highly and judged as rigorously as ordinary papers, but using somewhat different criteria. In particular, a pearl is not required to report original research, but, it should be concise, instructive, and entertaining. A pearl is likely to be rejected if its readers get bored, if the material gets too complicated, if too much-specialised knowledge is needed, or if the writing is inelegant. The key to writing a good pearl is polishing. A submission that is intended to be treated as a pearl must be marked as such on the submission web page and should contain the words "Functional Pearl" somewhere in its title or subtitle. These steps will alert reviewers to use the appropriate evaluation criteria. Pearls will be combined with ordinary papers, however, for the purpose of computing the conference's acceptance rate. #### Experience Reports The purpose of an Experience Report is to describe the experience of using functional programming in practice, whether in industrial application, tool development, programming education, or any other area. Possible topics for an Experience Report include, but are not limited to: * insights gained from real-world projects using functional programming * comparison of functional programming with conventional programming in the context of an industrial project or a university curriculum * project-management, business, or legal issues encountered when using functional programming in a real-world project * curricular issues encountered when using functional programming in education * real-world constraints that created special challenges for an implementation of a functional language or for functional programming in general An Experience Report is distinguished from a normal PACMPL issue ICFP paper by its title, by its length, and by the criteria used to evaluate it. * Both in the papers and in any citations, the title of each accepted Experience Report must end with the words "(Experience Report)" in parentheses. The acceptance rate for Experience Reports will be computed and reported separately from the rate for ordinary papers. * Experience Report submissions can be at most 12 pages long, excluding bibliography. * Each accepted Experience Report will be presented at the conference, but depending on the number of Experience Reports and regular papers accepted, authors of Experience Reports may be asked to give shorter talks. * Because the purpose of Experience Reports is to enable our community to understand the application of functional programming, an acceptable Experience Report need not add to the body of knowledge of the functional-programming community by presenting novel results or conclusions. It is sufficient if the Report describes an illuminating experience with functional programming, or provide evidence for a clear thesis about the use of functional programming. The experience or thesis must be relevant to ICFP, but it need not be novel. The review committee will accept or reject Experience Reports based on whether they judge the paper to illuminate some aspect of the use of functional programming. Anecdotal evidence will be acceptable provided it is well-argued and the author explains what efforts were made to gather as much evidence as possible. Typically, papers that show how functional programming was used are more convincing than papers that say only that functional programming was used. It can be especially effective to present comparisons of the situations before and after the experience described in the paper, but other kinds of evidence would also make sense, depending on context. Experience drawn from a single person's experience may be sufficient, but more weight will be given to evidence drawn from the experience of groups of people. An Experience Report should be short and to the point. For an industrial project, it should make a claim about how well functional programming worked and why; for a pedagogy paper, it might make a claim about the suitability of a particular teaching style or educational exercise. Either way, it should produce evidence to substantiate the claim. If functional programming worked in this case in the same ways it has worked for others, the paper need only summarise the results — the main part of the paper should discuss how well it worked and in what context. Most readers will not want to know all the details of the experience and its implementation, but the paper should characterise it and its context well enough so that readers can judge to what degree this experience is relevant to their own circumstances. The paper should take care to highlight any unusual aspects; specifics about the experience are more valuable than generalities about functional programming. If the paper not only describes experience but also presents new technical results, or if the experience refutes cherished beliefs of the functional-programming community, it may be better to submit it as a full paper, which will be judged by the usual criteria of novelty, originality, and relevance. The Program Chair will be happy to advise on any concerns about which category to submit to. ### ICFP Organisers General Chair: Nikhil Swamy (Microsoft Research, USA) Programme Chair: Sam Lindley (The University of Edinburgh, Scotland) Publicity Chair: Ilya Sergey (National University of Singapore, Singapore) Accessibility Co-Chairs: Vadim Zaliva (University of Cambridge, UK) and Calvin Beck (University of Pennsylvania, USA) Artifact Evaluation Chair: Jannis Limpberg (Vrije Universiteit Amsterdam, Netherlands) Diversity Chair: Daan Leijen (Microsoft Research, USA) Industrial Relations Co-Chairs: Atze Dijkstra (Standard Chartered Bank, England) and Mathieu Bosepflug (Tweag I/O, France) Programming Contest Co-Organisers: Alperen Keles (University of Maryland, USA) and Aymeric Fromherz (Inria, France) Student Research Competition Chair: Daniel Hillerström (The University of Edinburgh, Scotland) Video Chair: Apoorv Ingle (Iowa, USA) Workshops Co-Chairs: Arther Azevedo de Amorim (Boston University, USA) and Yannick Forster (Inria, France) ### PACMPL Volume 7, Issue ICFP 2023 Associate Editor: Sam Lindley (The University of Edinburgh, Scotland) Review Committee: Aggelos Biboudis, Oracle, Switzerland Alan Jeffrey, Roblox, USA Amos Robinson, Unaffiliated, Australia Andreea Costea, National University of Singapore, Singapore Andrew Hirsch, University of Buffalo, USA Andy Gill, Cerebrus Systems, USA Armando Solar-Lezama, MIT, USA Arnaud Spiwack, Tweag, France Benjamin C. Pierce, University of Pennsylvania, USA Beta Ziliani, FAMAF, UNC and Manas.Tech, Argentina Chung-Kil Hur, Seoul National University, South Korea Delia Kesner, Université de Paris, France Dylan McDermott, Reykjavik University, Iceland Éric Tanter, University of Chile, Chile Gabriel Radanne, Inria, France Gerwin Klein, Proofcraft & UNSW Sydney, Australia Hannah Gommerstadt, Vasser College, USA James Chapman, Input Output, Scotland James McKinna, Heriot-Watt, Scotland Jan Midtgaard, Tarides, Denmark Jeremy Gibbons, University of Oxford, England Jonathan Brachthäuser, University of Tübingen, Germany Jonathan Sterling, Aarhus University, Denmark José Pedro Magalhães, Standard Chartered Bank, England Josh Berdine, Meta UK, England Kathrin Stark, Heriot-Watt, Scotland Laura Bocchi, Kent, England Lennart Augustsson, Epic Games, Sweden Liang-Ting Chen, Academia Sinica, Taiwan, Taiwan Lionel Parreaux, HKUST, Hong Kong Marcos Viera, Universidad de la República, Uruguay Matthew Flatt, University of Utah, USA Michael D. Adams, National University of Singapore, Singapore Michael Greenberg, Stevens Institute of Technology, USA Niki Vazou, IMDEA, Spain Oliver Bračevac, Purdue University, USA Patrik Jansson, CSE, Chalmers and UGOT, Sweden, Sweden Paul Downen, UMass Lowell, USA Peter Thiemann, University of Freiburg, Germany Sam Tobin-Hochstadt, Indiana University, USA Satnam Singh, Groq, USA Sean Moss, Oxford, England Sebastian Erdweg, JGU Mainz, Germany Shin-ya Katsumata, National Institute of Informatics, Japan Simon Gay, University of Glasgow, Scotland Sonia Marin, University of Birmingham, England Stephen Dolan, Jane Street, England Susmit Sarkar, University of St Andrews, Scotland Tahina Ramananandro, Microsoft, USA Takeshi Tsukada, Chiba University, Japan Talia Ringer, University of Illinois at Urbana-Champaign, USA Yukiyoshi Kameyama, University of Tsukuba, Japan Zhenjiang Hu, Peking University, China

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Midlands Graduate School, 2-6 April 2023, Birmingham , UK
by Graham Hutton 14 Feb '23

14 Feb '23

Dear all, Registration is now open for this years Midlands Graduate School, which takes place 2-6 April 2023 at the University of Birmingham, UK: http://www.tinyurl.com/MGS2023 MGS provides an intensive course of lectures on the Mathematical Foundations of Computing. It has been running for approaching 25 years, and attracts around 100 participants per year from both academia and industry. This year's courses: - Domain theory and denotational semantics (Tom de Jong) - Type theory (Thorsten Altenkirch) - Category theory (Nicolai Kraus) - Computational models of higher categories (Jamie Vicary) - Homotopy type theory (Eric Finster) - String diagrams (Dan Marsden) - Algebraic semantics and verification (Georg Struth) - Effects and call-by-push-value (Paul Levy) Spaces are limited, so early registration is recommended. Please share! 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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Generic use of queries postgresql-simple
by Pietro Grandinetti 12 Feb '23

12 Feb '23

Hello-- I use postgresql-simple and for selecting rows from one table I have the following function. runMyQuery :: Connection -> String -- query with '?' params to bind -> Int -- first param -> Int -- second param -> IO [MyTable1] runMyQuery conn dbQuery param1 param2 = query conn dbQuery $ (param2, param2) data MyTable1 = MyTable1 {col1 :: Int, col2 :: Int, col3 :: String} instance FromRow MyTable1 where fromRow = MyTable1 <$> field <*> field <*> field There are some things I'd like to improve: 1. I will have to write "MyTable1", "MyTable2", ... datatypes, one for each table, but would like to have only one function runMyQuery where the return type is a generic IO [MyModel]. My problem is that I don't know how to write it for tables with different number of columns and different SQL types. 2. The 2nd to the penultimate arguments of runMyQuery are the arguments to bind into the SQL string query. This means that I should write several different version of "runMyQuery" each with a different number of arguments, but would like to have only one. Can you recommend some approaches? Thanks.

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Paillier package maintainership
by Abhiroop Sarkar 12 Feb '23

12 Feb '23

Hello, The package Paillier (https://hackage.haskell.org/package/Paillier<https://hackage.haskell.org/package/Paillier)> ) that provides a basic Paillier partial homomorphic encryption scheme hasn't seen any updates since 2016. The package, as of now, is very simple and cannot handle very common payloads in Machine Learning examples such as real numbers or even negative Integers. If the original maintainer Mr Li-Ting Tsai is no longer actively maintaining the package, I can take over, add support for real numbers (that is a non-trivial task) and add documentation to the package. I am not aware of any contact information for the author. Kindly let me know if there is any way to contact the author to transfer the maintainership. Best wishes, Abhiroop

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[Haskell] [ANNOUNCE] GHC 9.2.6 released
by Zubin Duggal 10 Feb '23

10 Feb '23

The GHC developers are happy to announce the availability of GHC 9.2.6. Binary distributions, source distributions, and documentation are available at [downloads.haskell.org](https://downloads.haskell.org/ghc/9.2.6). Download Page: https://www.haskell.org/ghc/download_ghc_9_2_6.html Blog Post: https://www.haskell.org/ghc/blog/20230210-ghc-9.2.6-released.html This release is primarily a bugfix release addressing a few issues found in 9.2.5. These include: * Fixes for a number of simplifier issues typically resulting in compiler panics (#22491, #22482, #19824, #22718, #22662, #22039). * Fix for a simplifier regression in 9.2.5 that could impact runtime performance when compiling with optimisations due to duplication of expensive work (#22425). * Various stability improvments and bug fixes for the non moving and parallel GCs (#22528, #20221, #22264, #22327, #22929, #22927, #22929, #22930). * Allow certain keywords which can be used as variable names with `-XOverloadedRecordDot` (#20723). * Improvements to typechecker performance for modules with holes in type signatures (#14766) * Bump `gmp-tarballs` to a version which doesn't use the reserved `x18` register on AArch64/Darwin systems, and also has fixes for CVE-2021-43618 (#22497, #22789). * ... and a few more. See the [release notes] for a full accounting. As some of the fixed issues do affect correctness users are encouraged to upgrade promptly. We would like to thank Microsoft Azure, GitHub, IOG, the Zw3rk stake pool, Well-Typed, Tweag I/O, Serokell, Equinix, SimSpace, Haskell Foundation, and other anonymous contributors whose on-going financial and in-kind support has facilitated GHC maintenance and release management over the years. Finally, this release would not have been possible without the hundreds of open-source contributors whose work comprise this release. As always, do give this release a try and open a [ticket][] if you see anything amiss. Happy compiling, - Zubin [ticket]: https://gitlab.haskell.org/ghc/ghc/-/issues/new [release notes]: https://downloads.haskell.org/~ghc/9.2.6/docs/html/users_guide/9.2.6-notes.…

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HKD and Generic
by PICCA Frederic-Emmanuel 09 Feb '23

09 Feb '23

Hello, I have this class DataSource data family DataSourcePath a :: Type data family DataSourceAcq a :: Type class DataSource a where withDataSourceP :: (Location l, MonadSafe m) => l -> DataSourcePath a -> (DataSourceAcq a -> m r) -> m r The purpose is to acquire a ressources from a data source path (for example, in a hdf5 file, "hdf5://path/to/my/dataset" I need to obtain a C struct which point on the Dataset) and then do something with this ressources Here an example of an instance in order to extract an Angstrom from a file or provide directly the constant value. -- Angstrom data instance DataSourcePath Angstrom = DataSourcePath'Angstrom (Hdf5Path Z Double) | DataSourcePath'Angstrom'Const Angstrom deriving (Eq, Generic, Show, FromJSON, ToJSON) data instance DataSourceAcq Angstrom = DataSourceAcq'Angstrom Dataset | DataSourceAcq'Angstrom'Const Angstrom instance DataSource Angstrom where withDataSourceP f (DataSourcePath'Angstrom p) g = withHdf5PathP f p $ \ds -> g (DataSourceAcq'Angstrom ds) withDataSourceP _ (DataSourcePath'Angstrom'Const a) g = g (DataSourceAcq'Angstrom'Const a) next, I build a bunch of DataFrame which contain all these ressources. data DataFrameQCustom = DataFrameQCustom Attenuation -- attenuation Geometry -- geometry Image -- image Index -- timestamp in double deriving Show data instance DataSourcePath DataFrameQCustom = DataSourcePath'DataFrameQCustom (DataSourcePath Attenuation) (DataSourcePath Geometry) (DataSourcePath Image) (DataSourcePath Index) deriving (Eq, Generic, Show, FromJSON, ToJSON) data instance DataSourceAcq DataFrameQCustom = DataSourceAcq'DataFrameQCustom (DataSourceAcq Attenuation) (DataSourceAcq Geometry) (DataSourceAcq Image) (DataSourceAcq Index) Indded I now need to write the withDataSource instance by hand instance DataSource DataFrameQCustom where withDataSourceP f (DataSourcePath'DataFrameQCustom a g i idx) gg = withDataSourceP f a $ \a' -> withDataSourceP f g $ \g' -> withDataSourceP f i $ \i' -> withDataSourceP f idx $ \idx' -> gg (DataSourceAcq'DataFrameQCustom a' g' i' idx') this seems so mechanical that I am wondring if this should not be automatize via Generic. Another point would be to avoiding mistake when writting the DatasourcePath instance and Generate the from an uniq structure using HKD Something like -- "Higher-Kinded Data" type family HKD f a where HKD Identity a = a HKD f a = f a data DataFrameHkl' f = DataFrameHkl (HKD f DataFrameQCustom) (HKD f Sample) deriving (Generic) type DataFrameHkl = DataFrameHkl' Identity type DataFrameHklPath = DataFrameHkl' DataSourcePath so I would like your help in order to write first a Generic version of withDataSourceP I read this https://reasonablypolymorphic.com/blog/higher-kinded-data/ but I am not completly sure how to convert my withDataSourceP :: (Location l, MonadSafe m) => l -> DataSourcePath a -> (DataSourceAcq a -> m r) -> m r signature into something Generic Thanks for considering Fred

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Volunteers wanted to administer a security advisory DB for Hackage
by David Christiansen 09 Feb '23

09 Feb '23

Hello fellow Haskellers, The HF is in the process of getting a security advisory database up and running for Haskell libraries, to enable both automated and manual audit workflows. We're looking for volunteers to help administer the database. If you have a background in security and would like to make a high-impact positive contribution to the Haskell ecosystem, please consider volunteering! More details are available at https://discourse.haskell.org/t/call-for-nominations-haskell-security-respo… . Thanks in advance! All the best, David Thrane Christiansen Executive Director The Haskell Foundation

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Haskell Tiny Game Jam!
by Simon Michael 07 Feb '23

07 Feb '23

The first Haskell Tiny Game Jam is now open! All welcome! Your mission: make Haskell games in 10 lines. https://github.com/haskell-game/tiny-games-hs and the #haskell-game chat room await your entries. Best, -Simon

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[ANN] Yampa-0.14.1
by Ivan Perez 07 Feb '23

07 Feb '23

Dear all, I'm happy to announce the release of Yampa 0.14.1! Yampa is a fast, elegant Functional Reactive Programming implementation. Yampa prides itself in being a long-standing community project. It has now been around for 20 years!!! This is probably the largest release to the Yampa project in a decade: The unit tests for all of Yampa's public API are now complete. Many of the new tests are implemented using QuickCheck, and care has been taken, whenever possible, to express the properties based on the continuous-time (FRP) interpretation of Yampa's primitives and combinators. Hopefully, this battery of tests will help speed up the process of accepting new features and changes, and will free resources that can be dedicated to investigating other issues. See https://github.com/ivanperez-keera/yampa#features for details on Yampa's features. * Summary of Version 0.14.1 - Complete remaining unit tests for all public API. - Fix typo in documentation.- Fix broken links in documentation. As always, Yampa and yampa-test are released in sync. For details, see: - https://github.com/ivanperez-keera/Yampa/releases/tag/v0.14.1 - https://github.com/ivanperez-keera/Yampa/blob/develop/yampa/CHANGELOG - https://github.com/ivanperez-keera/Yampa/blob/develop/yampa-test/CHANGELOG * Releases You can explore the current versions at: - https://hackage.haskell.org/package/Yampa - https://hackage.haskell.org/package/yampa-test * Code The github repo is located at: https://github.com/ivanperez-keera/Yampa * What's coming This release comes exactly 2 months after the last release. The next release is planned for Apr 7, 2023. There are several issues open that you can contribute to: https://github.com/ivanperez-keera/Yampa/issues Following our roadmap, the pending changes remain as follows: - Full conformance to style guide. - Removal of unnecessarily exposed elements from the interface (e.g., FRP.Yampa.Arrow.arr3) that are not used and belong in other libraries. This topic is open to discussion. - Benchmarks: Facilitate making sound, evidence-based decisions about suggested improvements to the implementation, by completing a series of benchmarks. - New mailing list: We will in the future lose access to Yale's CS department-based mailman list, and are thinking of the best place to move the mailing list to. * Donations Our project is now seeking donations to help continue developing Yampa, create new open source libraries, new material, and give talks. Special thanks go to @johannes-riecken for sponsoring my work on the Yampa project with a regular contribution. Github will match the first 5K donated, so if you donate $1/month, github will donate the same amount. No donation is too small. Any contribution will absolutely help. See https://github.com/sponsors/ivanperez-keera for details. If you can help, please come forward. All the best, Ivan

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function composition and Rank2Types
by Olaf Klinke 04 Feb '23

04 Feb '23

Dear Cafe, I used to believe that f . g $ x is equivalent to f $ g x but apparently that is not the case when rank-2 types are involved. Counterexample: {-# LANGUAGE RankNTypes #-} type Cont = forall r. (() -> r) -> r data Foo = Foo Cont mkCont :: () -> Cont mkCont x = \f -> f x foo1 :: () -> Foo foo1 x = Foo $ mkCont x foo2 :: () -> Foo foo2 x = Foo . mkCont $ x The function foo1 type-checks, the function foo2 doesn't. And that is although ghci tells me that mkCont :: () -> Cont Foo :: Cont -> Foo so I should be able to compose? What is going on here? GHC 9.0.2 errors with • Couldn't match type ‘b0’ with ‘Cont’ Expected: b0 -> Foo Actual: Cont -> Foo Cannot instantiate unification variable ‘b0’ with a type involving polytypes: Cont • In the first argument of ‘(.)’, namely ‘Foo’ In the expression: Foo . mkCont and GHC 8.8.4 errors with • Couldn't match type ‘(() -> r0) -> r0’ with ‘Cont’ Expected type: ((() -> r0) -> r0) -> Foo Actual type: Cont -> Foo • In the first argument of ‘(.)’, namely ‘Foo’ In the expression: Foo . mkCont The latter suggests that r is unnecessarily specialized to some specific-yet-unknown r0 which destroys the universal quantification. Olaf

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