July 2024 - Haskell-Cafe

Perl Regular Expressions
by Henning Thielemann 09 Jul '24

09 Jul '24

There is an overview page for regular expression libraries in Haskell. [1] However, the last substantial update is from 2014. It seems that regex-pcre was quite popular, but it binds to the C library libpcre which is being phased out in favor of pcre2. There are bindings to pcre2 in the Hackage package pcre2, but there seems to be unresolved low-level problems. [2] I am looking for a package where speed is not top priority, but compatibility to libpcre regular expressions. I think a plain Haskell package would increase the chances of absence of memory bugs and interfacing issues. According to the Wiki page Haskell-only implementations seem to prefer Posix expressions over Perl ones. [1] https://wiki.haskell.org/Regular_expressions [2] https://github.com/sjshuck/hs-pcre2/issues/34

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Call for Talks: Haskell Implementors' Workshop 2024
by Matthew Pickering 08 Jul '24

08 Jul '24

``` ACM SIGPLAN Haskell Implementors' Workshop https://icfp24.sigplan.org/home/hiw-2024 Milan, Italy, September 2, 2024 Co-located with ICFP 2024 https://icfp24.sigplan.org/ ``` ## Important dates * Deadline: July 19, 2024 (AoE) * Notification: August 2, 2024 * Workshop: September 2, 2024 The 16th Haskell Implementors’ Workshop is to be held alongside ICFP 2024 this year in Milan. It is a forum for people involved in the design and development of Haskell implementations, tools, libraries, and supporting infrastructure to share their work and to discuss future directions and collaborations with others. Talks and/or demos are proposed by submitting an abstract, and selected by a small program committee. There will be no published proceedings. The workshop will be informal and interactive, with open spaces in the timetable and room for ad-hoc discussion, demos, and lightning talks. ## Scope and Target Audience It is important to distinguish the Haskell Implementors’ Workshop from the Haskell Symposium which is also co-located with ICFP 2024. The Haskell Symposium is for the publication of Haskell-related research. In contrast, the Haskell Implementors’ Workshop will have no proceedings – although we will aim to make talk videos, slides, and presented data available with the consent of the speakers. The Implementors’ Workshop is an ideal place to describe a Haskell extension, describe works-in-progress, demo a new Haskell-related tool, or even propose future lines of Haskell development. Members of the wider Haskell community are encouraged to attend the workshop – we need your feedback to keep the Haskell ecosystem thriving. Students working with Haskell are especially encouraged to share their work. The scope covers any of the following topics. There may be some topics that people feel we’ve missed, so by all means submit a proposal even if it doesn’t fit exactly into one of these buckets: * Compilation techniques * Language features and extensions * Type system implementation * Concurrency and parallelism: language design and implementation * Performance, optimization and benchmarking * Virtual machines and run-time systems * Libraries and tools for development or deployment ## Talks We invite proposals from potential speakers for talks and demonstrations. We are aiming for 20-minute talks with 5 minutes for questions and changeovers. We want to hear from people writing compilers, tools, or libraries, people with cool ideas for directions in which we should take the platform, proposals for new features to be implemented, and half-baked crazy ideas. Please submit a talk title and abstract of no more than 300 words. Submissions can be made via HotCRP at https://hiw2024.hotcrp.com until July 19 (anywhere on earth). We will also have a lightning talks session. These have been very well received in recent years, and we aim to increase the time available to them. Lightning talks should be ~7mins and are scheduled on the day of the workshop. Suggested topics for lightning talks are to present a single idea, a work-in-progress project, a problem to intrigue and perplex Haskell implementors, or simply to ask for feedback and collaborators. ## Program Committee * Matthew Pickering (Well-Typed LLP) * David Binder (University of Tübingen) * Gabriella Gonzalez (Mercury) * Sylvain Henry (IOG) * Teofil Camarasu (Tracsis) ## Contact * Matthew Pickering

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a tribute to Haskell Curry
by Mark McConnell 06 Jul '24

06 Jul '24

Haskell Curry was a professor for 37 years at the Pennsylvania State University. Curry Hall is a dormitory named after him. On a recent visit to Penn State, my laptop asked me to help it take a selfie.

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[ANN] cabal-install-3.12.1.0 (and accompanying libraries) released
by Artem Pelenitsyn 06 Jul '24

06 Jul '24

Dear all, The cabal release team brings you the release of the cabal-install tool, version 3.12.1.0. This is the first release of the tool in the 3.12 series, and, hence, the first cabal-install supporting Cabal 3.12 packaged with GHC 9.10.1. We also update the three main libraries. - cabal-install: The command-line interface for Cabal and Hackage. <https://hackage.haskell.org/package/cabal-install-3.12.1.0> - Cabal: A framework for packaging Haskell software <https://hackage.haskell.org/package/Cabal-3.12.1.0> - Cabal-syntax: A library for working with .cabal files <https://hackage.haskell.org/package/Cabal-syntax-3.12.1.0> - cabal-install-solver: The command-line interface for Cabal and Hackage. <https://hackage.haskell.org/package/cabal-install-solver-3.12.1.0> The binaries for cabal-install are available on our website <https://downloads.haskell.org/cabal/cabal-install-3.12.1.0/> and can be installed via GHCup manually, e.g.: - Linux x86_64 (static, alpine3_18): ghcup --no-cache install cabal -u 'https://downloads.haskell.org/cabal/cabal-install-3.12.1.0/cabal-install-3.…' 3.12.1.0 - MacOS AArch64: ghcup --no-cache install cabal -u 'https://downloads.haskell.org/cabal/cabal-install-3.12.1.0/cabal-install-3.…' 3.12.1.0 - Windows: ghcup --no-cache install cabal -u 'https://downloads.haskell.org/cabal/cabal-install-3.12.1.0/cabal-install-3.…' 3.12.1.0 - or a similar command for your platform using the binaries provided on the website - as usual, cabal update && cabal install cabal-install-3.12.1.0 is an option too. We expect the official GHCup channel to be updated with the 3.12.1.0 binaries soon. <https://discourse.haskell.org/t/cabal-install-3-12-1-0-and-accompanying-lib…>What is new *Performance* - Significant speedups during cabal startup due to use of the latest tar *Project Organization* - Support for asm, cmm, and js sources in executable components - Support for per-component builds when coverage is enabled - Haskell files in explicit source directories take precedence over autogenerated Haskell files - Fix precedence for PATH for build-tools-depends (executables from PATH don’t shadow executables from build-tool-depends anymore) *UX* - Errors now have error codes, which will be documented on https://errors.haskell.org - A new subcommand, cabal path, which can be used to get information about the paths cabal will use within a project - Support for authentication tokens for uploading to Hackage - --(test-)show-details=direct is now the default - Shorten solver rejection messages by removing repetition - Show provenance of project constraints *Interaction with GHC* - Support for loading multiple components into one repl session - Support for the --semaphore flag to enable interaction with GHC Job Server protocol - Support for GHC2024 - Support for language extensions ExtendedLiterals¸ ListTuplePuns, and TypeAbstractions *Other Compilers* - Micro Haskell (MHS) has been added as a known compiler. We don’t have support for driving it yet, though. See the release notes <https://github.com/haskell/cabal/blob/master/release-notes/cabal-install-3.…> for more details and other changes. <https://discourse.haskell.org/t/cabal-install-3-12-1-0-and-accompanying-lib…> Contributors 50^2, Adam Gundry, Andrea Bedini, Andreas Abel, Andreas Klebinger, Arjun Kathuria, Artem Pelenitsyn, BasLaa, Bas Laarakker, Ben Gamari, Bodigrim, Brandon Chinn, brandon s allbery kf8nh, Bryan Richter, Colton Clemmer, Csaba Hruska, cydparser, Daniel Trstenjak, David Binder, David Christiansen, Edwin Marshall, Elodie Lander, Erik de Castro Lopo, Felix Yan, fendor, Finley, Francesco Ariis, Francesco Gazzetta, Fraser Tweedale, Gershom Bazerman, Hamish Mackenzie, Hécate Moonlight, Ikko Eltociear Ashimine, Jana Chadt, Javier Sagredo, Jean-Paul Calderone, Jens Petersen, Jessica Hamilton, John Paul Adrian Glaubitz, Josh Meredith, Julia Longtin, Julian Ospald, Kazuki Okamoto, Kristen Kozak, Krzysztof Gogolewski, liamzee, Liisi Kerik, Lin Runze, Malte Neuss, malteneuss, Marcin Szamotulski, Matthew Pickering, Mel Zuser, Michael Peyton Jones, Mike Pilgrem, Mikolaj Konarski, mixphix, Oleg Grenrus, Ondřej Šebek, Patrick Augusto, Patrick Dougherty, Peter Becich, Phil de Joux, Pierre Le Marre, Rebecca Turner, Rodrigo Mesquita, Ryan Scott, Samuel Thibault, Sander, Sebastian Tee, Sergey Vinokurov, Shae Erisson, sheaf, Simon Hengel, Siyuan Chen, Sören Tempel, SuganyaAK, Suganya Raju, Sylvain Henry, Taylor Fausak, Teo Camarasu, Tom Ellis, tomjaguarpaw, Tommy Bidne, Tom Smeding, Torsten Schmits, Tristan Cacqueray, Troels Henriksen, Wismill, Yvan Sraka, Zoe Zuser We thank all contributors as well as our reviewers, QA testers, devops, and others without whom this release wouldn’t be possible. <https://discourse.haskell.org/t/cabal-install-3-12-1-0-and-accompanying-lib…> Feedback Please, report any issues you notice with the 3.12.1.0 release on our GitHub: https://github.com/haskell/cabal — cabal release team (Artem, Brandon, Francesco, Gershom, Hécate, Mikołaj)

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2 optimization bugs ?
by George Colpitts 03 Jul '24

03 Jul '24

It seems like I have found two optimization bugs. Before filing bugs , I wanted to double check if others agreed and can reproduce the bugs. Compile and run the attached file: ghc -O2 optBugs.hs Loaded package environment from /Users/avie/.ghc/aarch64-darwin-9.10.1/environments/default [1 of 2] Compiling Main ( optBugs.hs, optBugs.o ) optBugs.hs:45:49: warning: [GHC-18042] [-Wtype-defaults] • Defaulting the type variable ‘b0’ to type ‘Integer’ in the following constraints (Integral b0) arising from a use of ‘^’ at optBugs.hs:45:49 (Num b0) arising from the literal ‘6’ at optBugs.hs:45:50 • In the first argument of ‘counts’, namely ‘(10 ^ 6)’ In the second argument of ‘(.)’, namely ‘counts (10 ^ 6)’ In the second argument of ‘(.)’, namely ‘elems . counts (10 ^ 6)’ | 45 | solve = product . map (+ 1) . elems . counts (10^6) -- 1000000 | ^ [2 of 2] Linking optBugs avie@Anabela-Air Documents % ./optBugs +RTS -s ./optBugs +RTS -s 39001250856960000 2,932,564,768 bytes allocated in the heap 143,405,696 bytes copied during GC 76,022,072 bytes maximum residency (4 sample(s)) 11,034,312 bytes maximum slop 164 MiB total memory in use (0 MiB lost due to fragmentation) Tot time (elapsed) Avg pause Max pause Gen 0 263 colls, 0 par 0.032s 0.036s 0.0001s 0.0020s Gen 1 4 colls, 0 par 0.048s 0.060s 0.0150s 0.0368s INIT time 0.003s ( 0.003s elapsed) MUT time 3.343s ( 3.333s elapsed) GC time 0.080s ( 0.096s elapsed) EXIT time 0.002s ( 0.008s elapsed) Total time 3.428s ( 3.440s elapsed) %GC time 0.0% (0.0% elapsed) Alloc rate 877,099,801 bytes per MUT second Productivity 97.5% of total user, 96.9% of total elapsed Now change the line solve = product . map (+ 1) . elems . counts (10^6) -- 1000000 to solve = product . map (+ 1) . elems . counts 1000000 save the file to disk, compile and rerun: ghc -O2 optBugs.hs Loaded package environment from /Users/avie/.ghc/aarch64-darwin-9.10.1/environments/default [1 of 2] Compiling Main ( optBugs.hs, optBugs.o ) [Source file changed] [2 of 2] Linking optBugs [Objects changed] avie@Anabela-Air Documents % ./optBugs +RTS -s ./optBugs +RTS -s 39001250856960000 1,920,053,000 bytes allocated in the heap 16,488 bytes copied during GC 8,028,224 bytes maximum residency (2 sample(s)) 393,152 bytes maximum slop 22 MiB total memory in use (0 MiB lost due to fragmentation) Tot time (elapsed) Avg pause Max pause Gen 0 239 colls, 0 par 0.000s 0.001s 0.0000s 0.0002s Gen 1 2 colls, 0 par 0.000s 0.001s 0.0007s 0.0011s INIT time 0.003s ( 0.003s elapsed) MUT time 2.011s ( 2.015s elapsed) GC time 0.001s ( 0.002s elapsed) EXIT time 0.000s ( 0.007s elapsed) Total time 2.015s ( 2.027s elapsed) %GC time 0.0% (0.0% elapsed) Alloc rate 954,738,679 bytes per MUT second Productivity 99.8% of total user, 99.4% of total elapsed Allocation decreased by a billion bytes and runtime has decreased by almost a third. This is hard to believe. The obvious explanation is that I dropped a zero when I wrote out 10^6 but I checked that I have six zeros. Also I get the same answer in both cases. Next uncomment the following two lines in factor: -- let p = sm ! m -- sm = smallest maxN and comment out the line: let p = smallest maxN ! m save the file, compile and rerun: ghc -O2 optBugs.hs Loaded package environment from /Users/avie/.ghc/aarch64-darwin-9.10.1/environments/default [1 of 2] Compiling Main ( optBugs.hs, optBugs.o ) [Source file changed] [2 of 2] Linking optBugs [Objects changed] avie@Anabela-Air Documents % ./optBugs +RTS -s ./optBugs +RTS -s 39001250856960000 16,051,152 bytes allocated in the heap 10,040 bytes copied during GC 44,328 bytes maximum residency (1 sample(s)) 29,400 bytes maximum slop 22 MiB total memory in use (0 MiB lost due to fragmentation) Tot time (elapsed) Avg pause Max pause Gen 0 2 colls, 0 par 0.000s 0.000s 0.0001s 0.0002s Gen 1 1 colls, 0 par 0.000s 0.001s 0.0015s 0.0015s INIT time 0.003s ( 0.003s elapsed) MUT time 0.019s ( 0.018s elapsed) GC time 0.000s ( 0.002s elapsed) EXIT time 0.001s ( 0.002s elapsed) Total time 0.023s ( 0.025s elapsed) %GC time 0.0% (0.0% elapsed) Alloc rate 866,786,478 bytes per MUT second Productivity 78.9% of total user, 72.5% of total elapsed Allocation has dropped from 2 billion bytes to 16 million and runtime has dropped from 2 seconds to 0.02 seconds. I think the optimizer should move the call to smallest outside of the "loop" in go. This seems like a bug to me.

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IFL 2024: Second Call for Papers
by Mart Lubbers 03 Jul '24

03 Jul '24

======================================================================= IFL 2024 36rd Symposium on Implementation and Application of Functional Languages venue: Radboud University Nijmegen, The Netherlands August 26 - 28 2024 https://ifl24.cs.ru.nl ======================================================================= ### Scope The goal of the IFL symposia is to bring together researchers actively engaged in the implementation and application of functional and function-based programming languages. IFL 2024 will be a venue for researchers to present and discuss new ideas and concepts, work in progress, and publication-ripe results related to the implementation and application of functional languages and function-based programming. ### Industrial track and topics of interest Topics of interest to IFL include, but are not limited to: - language concepts - type systems, type checking, type inferencing - compilation techniques - staged compilation - run-time function specialisation - run-time code generation - partial evaluation - (abstract) interpretation - meta-programming - generic programming - automatic program generation - array processing - concurrent/parallel programming - concurrent/parallel program execution - embedded systems - web applications - (embedded) domain specific languages - security - novel memory management techniques - run-time profiling performance measurements - debugging and tracing - virtual/abstract machine architectures - validation, verification of functional programs - tools and programming techniques ### Peer-review process Following IFL tradition, IFL 2024 will use a post-symposium review process to produce the formal proceedings. Before the symposium authors submit draft papers. These draft papers will be screened by the program chairs to make sure that they are within the scope of IFL. The draft papers will be made available to all participants at the symposium. Each draft paper is presented by one of the authors at the symposium. After the symposium, a formal review process will take place, conducted by the program committee. Reviewing is single blind. There will be at least 3 reviews per paper. The reviewers have 6 weeks to write their reviews. For the camera-ready version the authors can make minor revisions which are accepted without further reviewing. ### Important dates Submission deadline of draft papers August 4th, 2024 Notification of acceptance for presentation August 6th, 2024 Early registration deadline August 11th, 2024 Late registration deadline August 21th, 2024 IFL symposium August 26-28, 2024 Submission of papers for proceedings December 1st, 2024 Notification of acceptance February 2nd, 2025 Camera-ready version March 2nd, 2025 ### Submission details and Registration All contributions must be written in English. Papers must use the ACM two columns conference format, which can be found at: http://www.acm.org/publications/proceedings-template Submit your paper here: https://easychair.org/conferences/?conf=ifl20240 Registration https://ifl24.cs.ru.nl/Registration ### Peter Landin Prize The Peter Landin Prize is awarded to the best paper presented at the symposium every year. The honoured article is selected by the program committee based on the submissions received for the formal review process. The prize carries a cash award equivalent to 150 Euros. ### Organisation PC Chairs: Mart Lubbers Radboud University, The Netherlands Local Chairs: Peter Achten Radboud University, The Netherlands Sven-Bodo Scholz, Radboud University, The Netherlands ### Program committee: Benoît Montagu, University of Lorraine, Inria, France Christos Dimoulas, Northwestern University, USA Edsko de Vries, Well-typed, The Netherlands Fritz Henglein, University of Copenhagen, Denmark Ian Mackie, University of Sussex, UK Jason Hemann, Seton Hall University, USA João Saraiva, Universidade do Minho, Portugal Jurriaan Hage, Heriot-Watt University, UK Kenichi Asai, Ochanomizu University, Japan Maja Kirkeby, Roskilde University, Denmark Marco Morazán, Seton Hall University, USA Neil Mitchell, Facebook, UK Ralf Laemmel, University of Koblenz Landau, Germany Rinus Plasmeijer, TOP Software/Radboud University, The Netherlands Stephen Chang, UMass Boston, USA Tim Steenvoorden, Open University, The Netherlands Tom Schrijvers, KU Leuven, Belgium Yusuf Moosa Motara, Rhodes University, South Africa ### Venue IFL 2024 will be held physically in Nijmegen, the Netherlands. See the website for more information. https://ifl24.cs.ru.nl ### Acknowledgments This call-for-papers is an adaptation and evolution of content from previous instances of IFL. We are grateful to prior organisers for their work, which is reused here.

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[ANNOUNCE] GHC 9.6.6 is now available
by Zubin Duggal 01 Jul '24

01 Jul '24

The GHC developers are happy to announce the availability of GHC 9.6.6. Binary distributions, source distributions, and documentation are available on the [release page](https://www.haskell.org/ghc/download_ghc_9_6_6.html). Blog Post: https://www.haskell.org/ghc/blog/20240701-ghc-9.6.6-released.html This release is primarily a bugfix release addressing some issues found in the 9.6 series. These include: * A fix for a bug in the NCG that could lead to incorrect runtime results due to erroneously removing a jump instruction (#24507). * A fix for a linker error that manifested on certain platform/toolchain combinations, particularly darwin with a brew provisioned toolchain, arising due to a confusion in linker options between GHC and cabal (#22210). * A fix for a compiler panic in the simplifier due to incorrect eta expansion (#24718). * A fix for possible segfaults when using the bytecode interpreter due to incorrect constructor tagging (#24870). * And a few more fixes A full accounting of changes can be found in the [release notes]. 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 Hacking! -Zubin [ticket]: https://gitlab.haskell.org/ghc/ghc/-/issues/new [release notes]: https://downloads.haskell.org/~ghc/9.6.6/docs/users_guide/9.6.6-notes.html

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