- Haskell-Cafe - Haskell.org

runST $ unsafeIOToST $ ioWhatever
by Folsk Pratima 14 Apr '24

14 Apr '24

How wrong is it exactly? Did not get a reply on beginners(a)haskell.org import Control.Exception import Control.Monad.ST import Control.Monad.ST.Unsafe import Data.Word import Foreign.C.String import Foreign.C.String import Foreign.C.Types import Foreign.Marshal import Foreign.Ptr import Foreign.Storable foreign import ccall unsafe "strerror_r_portalbe.c strerror_r_portable" c_strerror_r :: CInt -> Ptr CChar -> CSize -> IO CInt memSet :: Ptr a -> Word8 -> Word32 -> IO (Ptr a) memSet ptr _ 0 = return ptr memSet ptr byte size = do let voidptr = castPtr ptr :: Ptr Word8 acts = map (\i -> pokeByteOff voidptr i byte) [0 .. fromIntegral (size - 1)] mapM_ id acts return ptr strError :: Int -> String strError errnum = runST $ unsafeIOToST ioString where baseSize :: CSize baseSize = 50 ioString = run baseSize run :: CSize -> IO String run size | size > 100000 = throwIO $ userError $ "!!! INTERNAL strError memory leak detected, " ++ "you can not recover !!!" | otherwise = do may <- tryIOString size case may of Just str -> return str Nothing -> run (size + baseSize) tryIOString :: CSize -> IO (Maybe String) tryIOString size = allocaBytes (fromIntegral size) $ \ptr -> do zeroptr <- memSet ptr 0 (fromIntegral size) st <- c_strerror_r (fromIntegral errnum) ptr size -- heuristic case st of 22 -> return . return $ "Unknown error " ++ show errnum 34 -> return Nothing _ -> peekCAString ptr >>= return . return main = mapM_ (putStrLn) $ map strError [1 .. 1000] The C file is #define _POSIX_C_SOURCE 200112L #include <string.h> int strerror_r (int, char *, size_t); int strerror_r_portable (int e, char *c, size_t s) { return strerror_r (e, c, s); } By default GHC picks up GNU version of strerror_r(), I want to pick up the default portable version. I do not know how to make GHC understand my desires.

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Ambiguous occurence error, despite use of DuplicateRecordFields (worked with ghc 8.10.7, not with 9.6.4)
by Han Joosten 10 Apr '24

10 Apr '24

Hi all, I am currently migrating a Haskell project that uses ghc 8.10.7 to ghc 9.6.4. Using the new version, I get errors like ~~~.haskell Ambiguous occurrence ‘pos’ It could refer to either the field ‘pos’ of record ‘PClassify’, defined at /workspaces/AmpersandNamespace/src/Ampersand/Core/ParseTree.hs:1265:5 or the field ‘pos’ of record ‘PPurpose’, defined at /workspaces/AmpersandNamespace/src/Ampersand/Core/ParseTree.hs:1186:5 or the field ‘pos’ of record ‘P_ViewSegment’, defined at /workspaces/AmpersandNamespace/src/Ampersand/Core/ParseTree.hs:1129:5 or the field ‘pos’ of record ‘P_ViewD’, defined at /workspaces/AmpersandNamespace/src/Ampersand/Core/ParseTree.hs:1080:5 or the field ‘pos’ of record ‘P_IdentDf’, defined at /workspaces/AmpersandNamespace/src/Ampersand/Core/ParseTree.hs:1024:5 or the field ‘pos’ of record ‘P_BoxItem’, defined at /workspaces/AmpersandNamespace/src/Ampersand/Core/ParseTree.hs:981:9 or the field ‘pos’ of record ‘TemplateKeyValue’, defined at /workspaces/AmpersandNamespace/src/Ampersand/Core/ParseTree.hs:959:5 or the field ‘pos’ of record ‘BoxHeader’, defined at /workspaces/AmpersandNamespace/src/Ampersand/Core/ParseTree.hs:947:5 or the field ‘pos’ of record ‘P_SubIfc’, defined at /workspaces/AmpersandNamespace/src/Ampersand/Core/ParseTree.hs:934:9 or the field ‘pos’ of record ‘P_Interface’, defined at /workspaces/AmpersandNamespace/src/Ampersand/Core/ParseTree.hs:899:5 or the field ‘pos’ of record ‘P_Population’, defined at /workspaces/AmpersandNamespace/src/Ampersand/Core/ParseTree.hs:870:9 or the field ‘pos’ of record ‘P_Rule’, defined at /workspaces/AmpersandNamespace/src/Ampersand/Core/ParseTree.hs:806:5 or the field ‘pos’ of record ‘PairViewSegment’, defined at /workspaces/AmpersandNamespace/src/Ampersand/Core/ParseTree.hs:740:9 or the field ‘pos’ of record ‘P_NamedRel’, defined at /workspaces/AmpersandNamespace/src/Ampersand/Core/ParseTree.hs:591:5 or the field ‘pos’ of record ‘PAtomPair’, defined at /workspaces/AmpersandNamespace/src/Ampersand/Core/ParseTree.hs:467:5 or the field ‘pos’ of record ‘Pragma’, defined at /workspaces/AmpersandNamespace/src/Ampersand/Core/ParseTree.hs:415:5 or the field ‘pos’ of record ‘P_Relation’, defined at /workspaces/AmpersandNamespace/src/Ampersand/Core/ParseTree.hs:408:5 or the field ‘pos’ of record ‘Representation’, defined at /workspaces/AmpersandNamespace/src/Ampersand/Core/ParseTree.hs:339:5 or the field ‘pos’ of record ‘PConceptDef’, defined at /workspaces/AmpersandNamespace/src/Ampersand/Core/ParseTree.hs:268:5 or the field ‘pos’ of record ‘P_Pattern’, defined at /workspaces/AmpersandNamespace/src/Ampersand/Core/ParseTree.hs:209:5 or the field ‘pos’ of record ‘Role’, defined at /workspaces/AmpersandNamespace/src/Ampersand/Core/ParseTree.hs:185:5 or the field ‘pos’ of record ‘P_RoleRule’, defined at /workspaces/AmpersandNamespace/src/Ampersand/Core/ParseTree.hs:172:5 or the field ‘pos’ of record ‘P_Enforce’, defined at /workspaces/AmpersandNamespace/src/Ampersand/Core/ParseTree.hs:152:5 or the field ‘pos’ of record ‘MetaData’, defined at /workspaces/AmpersandNamespace/src/Ampersand/Core/ParseTree.hs:136:5 Previously, it was totally fine to have different data types each have a field with the same name, as long as you used `DuplicateRecordFields` I have searched the migration documentation but I couldn't find any clue on why this has been changed or how to deal with it. I probably missed it. Any help is mostly appreciated! Thanks for reading Cheers, Han Joosten

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IFL 2024: First call for papers
by Mart Lubbers 09 Apr '24

09 Apr '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 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 ### 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: t.b.d. ### Venue IFL 2024 will be held physically in Nijmegen, the Netherlands. See the website for more information. https://ifl24.cs.ru.nl (under construction) ### 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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Agda Implementors' Meeting XXXVIII: Call for talks and participation
by mukesh tiwari 08 Apr '24

08 Apr '24

Dear all, The thirty-eighth Agda Implementors' Meeting will take place in Swansea, Wales, UK from Monday 13 to Saturday 18 May 2024. Wiki link for more details: https://wiki.portal.chalmers.se/ <https://wiki.portal.chalmers.se/agda/Main/AIMXXXVIII>agda <https://wiki.portal.chalmers.se/agda/Main/AIMXXXVIII>/Main/AIMXXXVIII <https://wiki.portal.chalmers.se/agda/Main/AIMXXXVIII> The meeting aims to bring together people not only developing but also using Agda or even those who are simply interested in it. We will have talks on the implementation details of Agda in the morning and code sprints in the afternoon. You can still submit your proposal for a talk or discussion! There's a (soft) deadline for registration on 14 April 2024 Registration instructions: https://wiki.portal.chalmers.se/ <https://wiki.portal.chalmers.se/agda/Main/AIMXXXVIII#Registration>agda <https://wiki.portal.chalmers.se/agda/Main/AIMXXXVIII#Registration> /Main/AIMXXXVIII#Registration <https://wiki.portal.chalmers.se/agda/Main/AIMXXXVIII#Registration> Best wishes, Anton Setzer ----------------------------------------------------------------------------- Dr Anton Setzer Darllenydd / Reader Ystafell / Room 403 Adran Gyfrifiadureg / Dept. of Computer Science Y Ffowndri Gyfrifiadurol / Computational Foundry Coleg Gwyddoniaeth / College of Science Prifysgol Abertawe/ Swansea University Campws y Bae/ Bay Campus Abertawe / Swansea SA1 8EN DU / UK Rhowch wybod i ni os hoffech dderbyn eich gohebiaeth yn Gymraeg. / Let us know if you would like to receive correspondence in Welsh. Rydym yn croesawu gohebiaeth yn Gymraeg neu yn Saesneg. / We welcome correspondence in Welsh or English. Ni fydd gohebu yn Gymraeg yn arwain at oedi./ Corresponding in Welsh will not lead to a delay.

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ICFP Programming Contest 2024
by ICFP Contest 2024 07 Apr '24

07 Apr '24

Dear Haskell community, The ICFP programming contest 2024 is is held from Friday 28 June 2024 at 12:00 UTC to Monday 1 July 2024 at 12:00 UTC. There will be a lightning division, ending on Saturday 29 June 2024 at 12:00 UTC. This is the 27th instance of the annual programming contest series sponsored by the ACM SIGPLAN International Conference on Functional Programming. This is an open online programming contest. Anybody may participate except for the contest organisers. No advance registration or entry fee is required. Contestants are free to organize themselves into teams of any size. Any programming language(s) on any platform(s) may be used. As a member of this community, you are all invited to participate. For more information and contact details, see https://icfpcontest2024.github.io/ We hope to see many of you on the scoreboard the end of June! Functional greetings, The ICFP Contest 2024 organising committee

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PL/Haskell?
by Matti Nykänen 04 Apr '24

04 Apr '24

It seems to be possible to invoke Haskell within PostgreSQL queries, see: <https://www.postgresql.org/about/news/plhaskell-v20-2597/> (1) Is it popular in the Haskell community? Or is it a proof-of-concept project to show that it can be done? (2) Does it have some easy-to-install packaging? All my initial attempts to follow the online installation instructions have resulted in aggravated lower back pain... -- Matti Nykänen

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PLDI 2024 - Call for Participation (Early registration: May 15)
by Yao Li 03 Apr '24

03 Apr '24

Call for Participation for PLDI 2024, the ACM SIGPLAN Conference on Programming Language Design and Implementation! ------------------------------------------------------------------------ PLDI is a premier forum for programming language research, broadly construed, including design, implementation, theory, applications, and performance. Come join us, online or in Copenhagen, Denmark, to discuss the latest programming languages research! * Website : https://pldi24.sigplan.org/attending/registration * Time : Mon 24--Fri 28 June 2024 * Place : Radisson Blu Scandinavia, Amager Boulevard 70, 2300 Copenhagen S, Denmark ### Important dates * Early Registration: 15th of May, 2024 ### Important rates (Registration rates include a 25% VAT; The prices displayed include tax) Registration rates (in-person) On or before 15 May, 2024 After 15 May, 2024 Regular (ACM or SIGPLAN member) €770.00 €850.00 Regular (non-member) €850.00 €935.00 Student (ACM or SIGPLAN member) €425.00 €505.00 Student (non-member) €475.00 €540.00 Registration rates (virtual) On or before 15 May, 2024 After 15 May, 2024 Regular (ACM or SIGPLAN member) €37.50 €50.00 Regular (non-member) €37.50 €50.00 Student (ACM or SIGPLAN member) €37.50 €50.00 Student (non-member) €37.50 €50.00 1-Day Pass (Co-Located events) On or before 15 May, 2024 After 15 May, 2024 Regular (ACM or SIGPLAN member) €225.00 €250.00 Regular (non-member) €250.00 €275.00 Student (ACM or SIGPLAN member) €150.00 €175.00 Student (non-member) €175.00 €200.00 ### Co-located events: Co-located Conferences: - ISMM, ACM SIGPLAN International Symposium on Memory Management https://conf.researchr.org/home/ismm-2024 - LCTES, ACM SIGPLAN/SIGBED International Conference on Languages, Compilers, and Tools for Embedded Systems https://pldi24.sigplan.org/home/LCTES-2024 Workshops: - ARRAY, the Array Programming Workshop https://pldi24.sigplan.org/home/ARRAY-2024 - CP, International Workshop on Choreographic Programming https://pldi24.sigplan.org/home/cp-2024 - EGRAPHS, the E-Graph Research, Applications, Practices, and Human-factors Symposium https://pldi24.sigplan.org/home/egraphs-2024 - Infer, the Infer Practitioners Workshop https://pldi24.sigplan.org/home/infer-2024 - PLMW, the Programming Languages Mentoring Workshop https://pldi24.sigplan.org/track/PLMW-PLDI-2024 - PODELSKI, PLDI 2024 Workshop Honoring Andreas Podelsk https://pldi24.sigplan.org/home/podelski-2024 - RTFM, Red-Hot Topics in Faculty Mentoring https://pldi24.sigplan.org/home/rtfm-2024 - SOAP, the ACM SIGPLAN International Workshop on the State Of the Art in Program Analysis https://pldi24.sigplan.org/home/SOAP-2024 - Sparse, the Sparse workshop (formerly CTSTA) https://pldi24.sigplan.org/home/sparse-2024 - WQS, Workshop on Quantum Software https://pldi24.sigplan.org/home/wqs-2024 Tutorials: https://pldi24.sigplan.org/track/pldi-2024-tutorials - Algorithms and Applications for Provable Repair of Deep Neural Networks Aditya V. Thakur - Concurrent Algorithms in Kotlin Coroutines Nikita Koval - Democratizing DSL development with the BuildIt Framework Ajay Brahmakshatriya, Saman Amarasinghe - PODELSKI Thomas Wies, Martin Schäf, Andrey Rybalchenko - Quick and dirty development of static analyses with LiSA Luca Negrini, Pietro Ferrara - Static Code Analysis with SootUp Eric Bodden, Markus Schmidt, Jonas Klauke, Kadiray Karakaya, Stefan Schott Student Research Competition! https://pldi24.sigplan.org/track/pldi-2024-src ### Student Volunteering Sign up to be a Volunteer and help us make PLDI 2024 a great experience for all attendants! https://pldi24.sigplan.org/track/pldi-2024-student-volunteering Apply here: https://forms.gle/QB9Tdmhr9v9ZPGx9A. The deadline is 15th of April. Best regards, Yao Li, Ph.D., (He/Him) Assistant Professor, Computer Science Department, Portland State University

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Announce: HsShellScript 3.6.4
by Volker Wysk 03 Apr '24

03 Apr '24

Hi! HsShellScript is a library that lets you do your Unix scripting in Haskell. It was outdated with respect to the supported compiler (meaning base- package) version, but now I've ported it to base >= 4.17.0.0 && < 5 (GHC 9.4/9.5). That's the recommended version (as of 2024-04-02). Here's the homepage: https://volker-wysk.de/hsshellscript/ Cheers, Volker

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Hackage: "Build: PlanningFailed"
by Volker Wysk 03 Apr '24

03 Apr '24

Hello I'm fighting with Hackage. To make things short, I've published my HsShellScript library (was a package candidate before). Here's the library's Hackage page: https://hackage.haskell.org/package/hsshellscript-3.6.2 And there's a button labeled "Build: PlanningFailed". When I click on it, I get the following messages under "Build Log": -----snip----- Resolving dependencies... Error: cabal: Could not resolve dependencies: [__0] trying: hsshellscript-3.6.2 (user goal) [__1] next goal: base (dependency of hsshellscript) [__1] rejecting: base-4.18.1.0/installed-4.18.1.0 (conflict: hsshellscript => base>=4.13.0 && <4.14) [__1] skipping: base-4.19.1.0, base-4.19.0.0, base-4.18.2.0, base-4.18.1.0, base-4.18.0.0, base-4.17.2.1, base-4.17.2.0, base-4.17.1.0, base-4.17.0.0, base-4.16.4.0, base-4.16.3.0, base-4.16.2.0, base-4.16.1.0, base-4.16.0.0, base-4.15.1.0, base-4.15.0.0, base-4.14.3.0, base-4.14.2.0, base-4.14.1.0, base-4.14.0.0 (has the same characteristics that caused the previous version to fail: excluded by constraint '>=4.13.0 && <4.14' from 'hsshellscript') [__1] rejecting: base-4.13.0.0, base-4.12.0.0, base-4.11.1.0, base-4.11.0.0, base-4.10.1.0, base-4.10.0.0, base-4.9.1.0, base-4.9.0.0, base-4.8.2.0, base-4.8.1.0, base-4.8.0.0, base-4.7.0.2, base-4.7.0.1, base-4.7.0.0, base-4.6.0.1, base-4.6.0.0, base-4.5.1.0, base-4.5.0.0, base-4.4.1.0, base-4.4.0.0, base-4.3.1.0, base-4.3.0.0, base-4.2.0.2, base-4.2.0.1, base-4.2.0.0, base-4.1.0.0, base-4.0.0.0, base-3.0.3.2, base-3.0.3.1 (constraint from non-upgradeable package requires installed instance) [__1] fail (backjumping, conflict set: base, hsshellscript) After searching the rest of the dependency tree exhaustively, these were the goals I've had most trouble fulfilling: base, hsshellscript -----snip----- Why does it reject the base library? The versions conflict, but why does it think the version should be base-4.18.1.0? The library compiles okay on my machine (using "cabal build"). I have this in the hsshellscript.cabal file, under "build-depends:": base >= 4.13.0 && < 4.14 I've got this version information from calling "cabal gen-bounds". Cheers, Volker

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Cabal: Can only one processor core be used?
by Volker Wysk 02 Apr '24

02 Apr '24

Hi I've searched the web and the cabal user guide on how to use more processor cores for compilation via cabal. I couldn't find anything. It looks like only one processor core can be used with cabal, even though (I've read on the web) GHC supports parallel compilation. Cabal compilation times can be a pain. It can't be that you can use only one processor core with cabal, can it ..? Cheers, Volker

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