- Haskell-Cafe - Haskell.org

SPLASH'24: Call for Volunteers
by Umar Farooq 24 Jun '24

24 Jun '24

======================================================================== Call for Volunteers The ACM Conference on Systems, Programming, Languages, and Applications: Software for Humanity (SPLASH'24) October 20-25, 2024, Pasadena, California, United States https://2024.splashcon.org/track/splash-2024-Volunteers ======================================================================== ### Important dates Volunteer applications Deadline: Tue Jul 30, 2024 Notification of Acceptance: Wed Aug 7, 2024 Apply to be a Volunteer and help us make SPLASH 2024 a great experience for all attendants! SPLASH 2024 is pleased to offer a number of opportunities for volunteers, who are vital to the efficient operation and continued success of the conference each year. The volunteer program is a chance for students and Programming Languages researchers aspirants from around the world to participate in the conferences while assisting us in preparing and running the event. The Volunteer Program helps more people attend the SPLASH conference by covering conference fees, including access to the banquet (but not travel or lodging expenses), in exchange for a fixed number of work hours (usually from 12 to 15) helping with the conference organization. ### Eligibility criteria Everyone is welcome to apply. Priority is given to junior members of our community, e.g. full- or part-time students of computer science and related fields. ### Duration Applicants must be available for at least five (5) full days between October 20th and October 25th 2024, and will be expected to provide 12-15 hours of volunteering work in that time. Volunteers may also be expected to be available for some amount of pre-conference discussion and training if necessary. Volunteers from all timezones are welcome. ### About Volunteering The skills, talents, and dedication of our Volunteers contribute to the overall quality of the conference. The Volunteer role this year will mainly involve working with the organizers to prepare for the conference by providing technical assistance to attendees, managing online Q&A and poster sessions, and supporting active communication in our online environment. Volunteering allows you to meet other people (faculty and students) in the Programming Languages (PL) Community. With several opportunities for networking, you can share ideas about your research, find topics you are passionate about, investigate career paths, and even find your future collaborators! ### Compensation - A Complimentary Conference Registration, offering access to all open sessions (i.e., parallel paper presentations, demonstrations, and workshops) and conference proceedings. - Free lunches and refreshments during breaks. - Volunteer shirt. - Free admission to all social events.

1 0

PLMW@ICFP'24: Final call for Participation (travel funding application by June 21)
by Ningning Xie 17 Jun '24

17 Jun '24

APPLICATION FOR PLMW TRAVEL FUNDING For full consideration for scholarship funding, please apply at the link below by June 21, AoE. We will notify accepted attendees in a rolling fashion until all funding is committed. The application can be accessed at the following URL (Apply by June 21, 2024 AOE for full consideration!): https://forms.gle/vC6udnMWRvvAczPR6 —-------------------------------------------------------------- ACM SIGPLAN Programming Languages Mentoring Workshop (PLMW) at ICFP 24, Milan, Italy Workshop: Monday, September 2, 2024 Website: https://icfp24.sigplan.org/home/PLMW-ICFP-2024 PLMW is a workshop co-located with ICFP 2024 (the International Conference on Functional Programming) in Milan, Italy, from September 2-7. The purpose of this mentoring workshop is to encourage graduate students and senior undergraduate students to pursue careers in programming language research. This workshop will bring together world leaders in programming languages research and teaching from academia and industry to help students imagine how they might contribute to our research community. Topics will range from the abstract (e.g., what is PL research and how does one become involved in it) to the concrete (e.g., how to navigate an academic conference, how to pick a research area) as well as technical talks on cutting-edge topics. We especially encourage women and underrepresented minority students, and people with disabilities to attend PLMW. This workshop is part of the activities surrounding ICFP, and takes place the day before the main conference. One goal of the workshop is to make the ICFP conference more accessible to newcomers. We hope that participants will stay through the entire conference. Note that ICFP and PLMW are planned to be largely in-person events. While we recognize that travel to conferences is not easy for everyone, we do hope you will be able to join us in person to get the most out of the conference and its community-building aspects. A number of sponsors have generously donated scholarship funds for qualified students to attend PLMW. These scholarships can cover expenses (airfare, hotel, and registration fees) for attendance at both the workshop and the ICFP conference. Students attending this year will get one year free student membership of SIGPLAN, unless they prefer to opt out during their application. The workshop registration is open to all. Students with alternative sources of funding are welcome as well.

1 0

[ANN] csound-expression-5.4.4 - music and sound design framework
by Anton Kholomiov 16 Jun '24

16 Jun '24

I'd like to announce a new release of [csound-expression]( https://github.com/spell-music/csound-expression) on [hackage]( https://hackage.haskell.org/package/csound-expression) The CE is a music framework for haskell with focus on ease of use and feature rich as it rides on top of the powerful audio programming language Csound. It is a DSL to build Csound programs. So the library embeds Csound in Haskell. It's a bug fix release. Many algorithms in the low-level renderer csound-expression-dynamic were rewritten and fixed. In the previous version unfortunately there were severe bugs in effectful expressions and in if-then-else blocks. But now they are fixed. Also I've updated the library to include new Csound opcodes (audio processing units from 6.18 version). Happy music making with Haskell! About the future of the csound-expression: I've started the implementation of a more tiny csound-core package. It offers a missing layer of low-level building of type-safe Csound expressions. In the previous version I've created lots of abstractions to make music making more pleasant for FP style. But this layering makes it kind of hard to debug rendered code. So I'd like to create a tiny imperative style core that will allow me to debug produced Csound code. And the rest of the code should be expressed in terms of this library. I'm not there yet. I've built the core library and it turned out very well. But now I need to rewrite FP abstractions on top of it. I'm not there yet. But I hope that gradually I will make it. Also I plan to deprecate GUI features as FLTK was deprecated in Csound and it's not packaged with Csound anymore. I think maybe it would be better to substitute them with JS+OSC. github: https://github.com/spell-music/csound-expression hackage: https://hackage.haskell.org/package/csound-expression

1 0

Datakind and instance
by PICCA Frederic-Emmanuel 14 Jun '24

14 Jun '24

Hello, I have a class class HasIniConfig where getConfig ... a kind using DataKind data ProjectionType = TypeA | TypeB ... I would like to create instance for each 'TypeX But when I try to write an instance I get this error src/Hkl/Binoculars/Projections/QCustom.hs:195:23: error: • Expected a type, but ‘'QCustomProjection’ has kind ‘ProjectionType’ • In the first argument of ‘HasIniConfig’, namely ‘'QCustomProjection’ In the instance declaration for ‘HasIniConfig 'QCustomProjection’ | 195 | instance HasIniConfig 'QCustomProjection where | ^^^^^^^^^^^^^^^^^^ I should add class HasIniConfig (a :: ProjectionType) where But in that cas I can not create instance for other type, and I need to :) I would be glade if someone could explain how to all this. Thanks Frederic

2 2

POPL 2025: Call for Workshops and Co-located Events
by Ningning Xie 13 Jun '24

13 Jun '24

CALL FOR WORKSHOPS AND CO-LOCATED EVENTS POPL 2025 52nd ACM SIGPLAN-SIGACT Symposium on Principles of Programming Languages Sun 19 - Sat 25, January 2025 Denver, Colorado, United States https://popl25.sigplan.org The 52nd ACM SIGPLAN-SIGACT Symposium on Principles of Programming Languages (POPL 2025) will be held in Denver, Colorado, United States. POPL provides a forum for the discussion of fundamental principles and important innovations in the design, definition, analysis, transformation, implementation and verification of programming languages, programming systems, and programming abstractions. Events focusing on experimental and theoretical topics are welcome. Proposals are invited for workshops and other events to be co-located with POPL 2025. All co-located events are sponsored by SIGPLAN ( http://acm.org/sigplan/) Workshops should be more informal and focused than POPL itself, and include sessions that enable interaction among the workshop attendees. The preference is for one-day workshops, but other schedules can also be considered. --------------------------------------------------------------------- Submission details Deadline for submission: 26 July 2024 Notification of acceptance: 2 August 2024 A workshop proposal should provide the following information: * Name of the workshop. * Duration of the workshop. * Whether the workshop will be Conference-approved or SIGPLAN-approved (see below). * Organizers: names, affiliation, contact information, brief (100 words) biography. * A short description (150-200 words) of the topic. * Event format: workshop; type of submissions if any; review process; results dissemination. * Expected attendance and target audience. * Potential PC members - please do not contact them before the workshop is approved. * History of the workshop. * Plans for remote participation Proposals must be submitted in PDF form by email with the subject POPL 2025 Workshop Proposal: [workshop name], to the workshop co-chairs: Christoph Matheja (chmat(a)dtu.dk) and Robert Rand (rand(a)uchicago.edu) --------------------------------------------------------------------- SIGPLAN Sponsorship POPL co-located events are sponsored by SIGPLAN (http://sigplan.org/) There are two kinds of co-located events: Conference-approved (no proceedings) and SIGPLAN-approved (proceedings in the ACM Digital Library). See http://www.sigplan.org/Resources/Guidelines/Workshops/ for more information, including a full listing of prescriptions for Conference-approved and SIGPLAN-approved workshops. SIGPLAN-approved workshops must respect the SIGPLAN Diversity Policy. Proposals for SIGPLAN-approved workshops must additionally include the gender, country of affiliation, and professional status of potential PC members. See https://www.sigplan.org/Resources/Policies/Diversity/ for more details. --------------------------------------------------------------------- Selection committee All submissions will be evaluated by a committee comprising the workshops co-chairs, the general chair, and the program chair. --------------------------------------------------------------------- Further information Any questions regarding POPL 2025 co-located event proposals should be addressed to the workshops chairs Christoph Matheja (chmat(a)dtu.dk) and Robert Rand (rand(a)uchicago.edu)

1 0

Call for Papers: SPLASH 2024 Student Research Competition
by Umar Farooq 07 Jun '24

07 Jun '24

======================================================================== SPLASH 2024 Student Research Competition Call for Papers Student Research Competition will be held as part of The ACM Conference on Systems, Programming, Languages, and Applications: Software for Humanity (SPLASH'24) October 20-25, 2024, Pasadena, California, United States https://2024.splashcon.org/track/splash-2024-SRC ======================================================================== ### Important dates Submission Deadline: Mon Jul 8, 2024 Author Notification: Mon Aug 19, 2024 Camera Ready: Sun Sep 1, 2024 The ACM Student Research Competition (SRC) offers a unique opportunity for undergraduate and graduate students to present their research to a panel of judges and conference attendees at SPLASH. The SRC provides visibility and exposes up-and-coming researchers to computer science research and the research community. This competition also gives students an opportunity to discuss their research with experts in their field, get feedback, and sharpen their communication and networking skills. ### Eligibility criteria Participants must have current student status, either graduate or undergraduate, at the time of the competition. Participants in the SRC must also be current ACM (student) members. ### Prizes Winners of the three top places in each category receive prizes of $500 for the first place winner, $300 for the second place winner and $200 for the third place winner, respectively. The top three undergraduate and graduate winners receive an award medal and a one-year complimentary ACM student membership with a subscription to ACM's Digital Library. ### ACM SRC Grand Finals First place winners in each category will be invited to participate in the ACM SRC Grand Finals, an online round of competition between first-place SRC winners from different ACM conferences held in 2024. Grand Finals will be judged by an ACM-appointed panel of judges. Winners of the three top Grand Finals places in each category will receive additional prizes of $500 for the first place winner, $300 for the second place winner and $200 for the third place winner, respectively. Winners of the SRC Grand Finals are recognized at the Annual ACM Awards Banquet along with prestigious ACM award winners, including the winner of the Turing Award. ##### Review Committee Review Committee Chairs: Anders Miltner, Simon Fraser University Jiasi Shen, The Hong Kong University of Science and Technology

1 0

2nd Call for Papers: ACM Workshop on Functional Software Architecture [Deadline June 3]
by Michael Sperber 04 Jun '24

04 Jun '24

====================================================================== *** FUNARCH 2024 -- CALL FOR PAPERS *** Second ACM SIGPLAN Workshop on Functional Software Architecture - FP in the Large 6th September 2024, Milan, Italy Co-located with ICFP 2024 https://functional-architecture.org/events/funarch-2024/ ====================================================================== TIMELINE: Paper submission 3rd June 2024 Author notification 30th June 2024 Camera ready copy 18th July 2024 Workshop 6th Sept 2024 BACKGROUND: "Functional Software Architecture" refers to methods of construction and structure of large and long-lived software projects that are implemented in functional languages and released to real users, typically in industry. The goals for the workshop are: - To assemble a community interested in software architecture techniques and technologies specific to functional programming; - To identify, categorize, and document topics relevant to the field of functional software architecture; - To connect the functional programming community to the software architecture community to cross-pollinate between the two. The workshop follows on from the Functional Software Architecture open space that was held at ICFP 2022 in Slovenia. SCOPE: The workshop seeks submissions in a range of categories: - You're a member of the FP community and have thought about how to support programming in the large, for example by framing functional ideas in architectural terms or vice verse, comparing different languages in terms of their architectural capabilities, clarifying architectural roles played by formal methods, proof assistants and DSLs, or observing how functional concepts are used in other language and architecture communities. Great, submit a research paper! - You're a member of the architecture community, and have thought about how your discipline might help functional programmers, for example by applying domain-driven design, implementing hexagonal architecture, or designing self-contained systems. Excellent, submit a research paper! - You've worked on a large project using functional programming, and it's worked out well, or terribly, or a mix of both; bonus points for deriving architectural principles from your experience. Wonderful, submit an experience report! - You know a neat architectural idiom or pattern that may be useful to others developing large functional software systems. Fabulous, submit an architectural pearl! - You have something that doesn't fit the above categories, but that still relates to functional software architecture, such as something that can be written up, or that could be part of the workshop format like a panel debate or a fishbowl. Superb, submit to the open category! Research 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 architectural pearls need not necessarily report original research results. The key criterion for such papers is that they make a contribution from which others can benefit. It is not enough simply to describe a large software system, or to present ideas that are specific to a particular system. Open category submissions that are not intended for publication are not required to follow the formatting guidelines, and can submit in PDF, word or plain text format as preferred. Not knowing what kinds of submissions we will receive, we cannot be specific as to how they will be evaluated. However, submissions that seem likely to stimulate discussion around practices in functional architecture are encouraged. If you are unsure whether your contribution is suitable, or if you need any kind of help with your submission, please email the program chairs at <funarch2024(a)easychair.org>. Papers must be submitted by 3rd June 2024 using the EasyChair submission page: https://easychair.org/my/conference?conf=funarch2024 Formatting: submissions intended for publication must be in PDF format and follow the ACM SIGPLAN style guidelines, using the acmart format and the sigplan sub-format. Please use the review option when submitting, as this enables line numbers for easy reference in reviews. For further details, see SIGPLAN's author information: http://www.sigplan.org/Resources/Author/#acmart-format If your submission is not a research paper, please mark this using a subtitle (Experience Report, Architectural Pearl, Open Category). Length: submissions must adhere to the limits specified below. However, there is no requirement or expectation that all pages are used, and authors are encouraged to strive for brevity. Research papers 5 to 12+ pages Architectural pearls 5 to 12 pages Experience reports 3 to 6 pages Open category 1 to 6 pages Publication: The proceedings of FUNARCH 2024 will be published in the ACM Digital Library, and authors of accepted papers are required to agree to one of the standard ACM licensing options. Accepted papers must be presented at the workshop by one of the authors, but in special cases we may consider remote presentation. 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. PROGRAM CHAIRS: Mike Sperber (Active Group, Germany) Perdita Stevens (University of Edinburgh, UK) PROGRAM COMMITTEE: Annette Bieniusa (University of Kaiserslautern) Jeffrey Young (IOG) Will Crichton (Brown University) Isabella Stilkerich (Schaeffler Technologies AG) Kiko Fernandez-Reyes (Ericsson) Ryan Scott (Galois) Satnam Singh (Groq) Facundo Dominguez (Tweag) Ilya Sergey (University of Singapore) Martin Elsman (University of Copenhagen) Benjamin Pierce (University of Pennsylvania) Matthew Flatt (University of Utah) Nada Amin (Harvard University) Richard Eisenberg (Jane Street) WORKSHOP VENUE: The workshop will be co-located with the ICFP 2024 conference at the Fiera Milano Congressi, Milan, Italy.

1 1

Exhaustive pattern match warning and GADTs
by William Yager 01 Jun '24

01 Jun '24

Hello cafe, I'm writing a bit of code with state machines that are only allowed to make certain types of transitions between certain classes of states (e.g. "ready" and "unready"). The state types have some type parameters describing which class of state it's currently in. The step functions look vaguely like `step :: state a -> input b -> state c`, with various constraints on `a`, `b`, and `c`. When `state` and `input` are GADTs, you can enforce interesting invariants about the output state, given the input state and event. This all seems to work fine, and seems to be getting me in the direction I want to go. However, I'm running into a roadblock (possibly a bug?). Take the following minimal example: {-# LANGUAGE DataKinds, GADTs #-} module Lib () where data State2 s a where State2T :: s True -> State2 s True State2F :: s False -> State2 s False data OnlyTrue s where TrueState :: OnlyTrue True example :: State2 OnlyTrue s -> () example (State2T TrueState) = () -- Comment this and get non-exhaustive pattern warning -- Uncomment this and get "Inaccessible code" warning -- example (State2F TrueState) = () There is only one possible pattern on the LHS of the equation. If I don't put the (impossible) pattern, GHC gives me a warning about missing a pattern. If I do put the impossible pattern, GHC warns me that the pattern is impossible. Indeed! So why is GHC complaining about it in the first place? I'm using GHC 9.6.5. Around 7-8 years ago, I wrote some similar code, using typeclasses to constraint GADTs, and I remember being very impressed that the completeness checker was smart enough to figure out not to complain about impossible patterns (cf the paper "GADTs meet their match"). This seems like a simpler use case than what I recall doing in the past, but the completeness checker is giving me bad warnings here. Any ideas what might be going wrong? Thanks, Will

2 2

Re: [Haskell-cafe] Issue building with ghc-9.8.2 and packages unix, directory, filepath and os-string
by Daniel Trstenjak 01 Jun '24

01 Jun '24

> The problem is that `--allow-newer` tells cabal to ignore dependencies' upper bounds > completely. If those bounds turn out to be necessary in some cases, the solver will produce a > bad build plan. Looking at the compile error of the unix package, it looks like it gets the wrong combination of filepath and os-string packages, resulting in the missing symbols. This depends on the os-string flag, either the unix package gets the older filepath package containing these symbols or the newer one without them and additionally the os-string package now containing the symbols. This handling with the os-string flag feels wrong to me and therefore cabal can‘t resolve the right dependencies. The unix 2.8.5.0 package has an upper bound for filepath of <1.5, the one with the symbols, but unix 2.8.5.1 has the lower bound filepath >1.4.100, therefore supporting the filepath packages with and without the symbols. It seems if unix 2.8.5.1 would only support the filepath package without the symbols, by having the lower bound filepath >=1.5, then cabal could work out the right dependencies. Is there a reason why the unix 2.8.5.1 does it that way?

3 2

Issue building with ghc-9.8.2 and packages unix, directory, filepath and os-string
by Daniel Trstenjak 31 May '24

31 May '24

Hi, I'm trying to get my program to compile with ghc-9.8.2. Raising the upper bounds of my dependencies I'm running into a compile error for the unix-2.8.5.1 package: [15 of 53] Compiling System.Posix.Env.PosixString ( /home/dan/sources/unix-2.8.5.1/dist-newstyle/build/x86_64-linux/ghc-9.8.2/unix-2.8.5.1/build/System/Posix/Env/PosixString.hs, /home/dan/sources/unix-2.8.5.1/dist-newstyle/build/x86_64-linux/ghc-9.8.2/unix-2.8.5.1/build/System/Posix/Env/PosixString.o, /home/dan/sources/unix-2.8.5.1/dist-newstyle/build/x86_64-linux/ghc-9.8.2/unix-2.8.5.1/build/System/Posix/Env/PosixString.dyn_o ) System/Posix/Env/PosixString.hsc:45:1: error: [GHC-87110] Could not load module ‘System.OsString.Internal.Types’. It is a member of the hidden package ‘os-string-2.0.3’. Perhaps you need to add ‘os-string’ to the build-depends in your .cabal file. It is a member of the hidden package ‘filepath-1.4.200.1’. Perhaps you need to add ‘filepath’ to the build-depends in your .cabal file. Use -v to see a list of the files searched for. | 45 | import System.OsString.Internal.Types | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ System/Posix/Env/PosixString.hsc:47:1: error: [GHC-61948] Could not find module ‘System.OsString.Data.ByteString.Short’. Perhaps you meant System.OsString.Data.ByteString.Short (needs flag -package-id os-string-2.0.3) System.OsPath.Data.ByteString.Short (needs flag -package-id filepath-1.4.200.1) System.OsString.Data.ByteString.Short.Word16 (needs flag -package-id os-string-2.0.3) | 47 | import qualified "os-string" System.OsString.Data.ByteString.Short as B | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ System/Posix/PosixPath/FilePath.hsc:50:1: error: [GHC-61948] Could not find module ‘System.OsString.Data.ByteString.Short’. Perhaps you meant System.OsString.Data.ByteString.Short (needs flag -package-id os-string-2.0.3) System.OsPath.Data.ByteString.Short (needs flag -package-id filepath-1.4.200.1) System.OsString.Data.ByteString.Short.Word16 (needs flag -package-id os-string-2.0.3) | 50 | import "os-string" System.OsString.Data.ByteString.Short as BSS | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ System/Posix/PosixPath/FilePath.hsc:55:1: error: [GHC-87110] Could not load module ‘System.OsString.Internal.Types’. It is a member of the hidden package ‘os-string-2.0.3’. Perhaps you need to add ‘os-string’ to the build-depends in your .cabal file. It is a member of the hidden package ‘filepath-1.4.200.1’. Perhaps you need to add ‘filepath’ to the build-depends in your .cabal file. Use -v to see a list of the files searched for. | 55 | import System.OsString.Internal.Types (PosixString(..), pattern PS) | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ I can get rid of this compile error and a similar one for the directory package by setting the flag os-string in my cabal.project file: constraints: unix +os-string, directory +os-string Now I'm wondering what is the right way to handle this case? Thanks for any hints! Greetings, Daniel

4 7