August 2025 - Haskell-Cafe

Takeover of AvlTree and COrdering
by Andrew Lelechenko 22 Aug '25

22 Aug '25

I’d like to take over Hackage packages https://hackage.haskell.org/package/COrdering and https://hackage.haskell.org/package/AvlTree. Last uploads were in 2008. Both packages fail to compile with modern GHCs; my intention is to bring them back to life. There are no maintainer contacts and no source code repository linked, so I cannot reach out to the maintainer to offer my services. Best regards, Andrew

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GHC 9.10.3-rc4 is now available
by Zubin Duggal 18 Aug '25

18 Aug '25

The GHC developers are very pleased to announce the availability of the fourth release candidate for GHC 9.10.3. Binary distributions, source distributions, and documentation are available at [downloads.haskell.org][] and via [GHCup](https://www.haskell.org/ghcup/). GHC 9.10.3 is a bug-fix release fixing over 50 issues of a variety of severities and scopes. A full accounting of these fixes can be found in the [release notes][]. As always, GHC's release status, including planned future releases, can be found on the GHC Wiki [status][]. The changes from the third release candidate are: - A fix for a rare segfault with code involving STM (#26205) - A fix for the `naturalAndNot` returning bogus results (#26205) - A fix for a crash in the renamer (#25056) This release candidate will have a two-week testing period. If all goes well the final release will be available the week of 1 September 2025. We would like to thank Well-Typed, Tweag I/O, Juspay, QBayLogic, Channable, Serokell, SimSpace, the 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. [release notes]: https://gitlab.haskell.org/ghc/ghc/-/blob/ghc-9.10/docs/users_guide/9.10.3-… [status]: https://gitlab.haskell.org/ghc/ghc/-/wikis/GHC-status [downloads.haskell.org] https://downloads.haskell.org/ghc/9.10.3-rc4 [ticket]: https://gitlab.haskell.org/ghc/ghc/-/issues/new

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GHC 9.10.3-rc3 is now available
by Zubin Duggal 08 Aug '25

08 Aug '25

The GHC developers are very pleased to announce the availability of the third release candidate for GHC 9.10.3. Binary distributions, source distributions, and documentation are available at [downloads.haskell.org][] and via [GHCup](https://www.haskell.org/ghcup/). GHC 9.10.3 is a bug-fix release fixing over 50 issues of a variety of severities and scopes. A full accounting of these fixes can be found in the [release notes][]. As always, GHC's release status, including planned future releases, can be found on the GHC Wiki [status][]. The changes from the second release candidate are: - Reverting a change the exports of the `Backtrace` constructor in the base library that was backported due to confusion on CLC approvals (!14587) - Reverting a change to the configure script (!14324) that dropped probing for ld.gold This release candidate will have a two-week testing period. If all goes well the final release will be available the week of 22 August 2025. We would like to thank Well-Typed, Tweag I/O, Juspay, QBayLogic, Channable, Serokell, SimSpace, the 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. [release notes]: https://gitlab.haskell.org/ghc/ghc/-/blob/ghc-9.10/docs/users_guide/9.10.3-… [status]: https://gitlab.haskell.org/ghc/ghc/-/wikis/GHC-status [downloads.haskell.org] https://downloads.haskell.org/ghc/9.10.3-rc3 [ticket]: https://gitlab.haskell.org/ghc/ghc/-/issues/new

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Correct parsers for bounded integral values
by Stefan Klinger 07 Aug '25

07 Aug '25

Hello everybody =) I've been bugged by the silent overflowing of integer parsers as provided by `base`, `attoparsec`, and others. I'd go so far as to call it a bug when the user types `298` and the parser says `Right 42`. Unfortunately, all parsing libraries I've looked at get this wrong. A [solution][4] is proposed below. I'm asking for feedback on how to continue from here. Kind regards Stefan The following examples can be reproduced with $ git clone 'https://github.com/s5k6/robust-int.git' $ cd robust-int $ cabal repl robust-int:demo Situation --------- This is the current situation with [read][1] from base: > read "298" :: Word8 42 And with [decimal][2] from attoparsec: > A.parseOnly (A.decimal :: A.Parser Word8) $ pack "298" Right 42 And the solution [usually suggested][5] for Parsec (which relies on `read`): parsecWord8 :: P.Parser Word8 parsecWord8 = read <$> P.many1 P.digit > P.runParser parsecWord8 () "" "298" Right 42 Even worse, the latter would rather exhaust memory than realise its input is way out of bounds: > P.runParser parsecWord8 () "" $ repeat '1' ⊥ Also, some 3rd-party libraries get this wrong, e.g., [parsec3-numbers][6]: > P.runParser (PN.decimal :: P.Parser Word8) () "" "298" Right 42 And [megaparsec][8], which is at least nice enough to warn about this in its documentation: > M.parseMaybe (M.decimal :: M.Parsec () String Word8) "298" Just 42 I find this misses the point of a parser validating its input. Solution -------- It is [possible to implement][7] parsers for bounded integral types which verify the bounds of the parsed value *while* parsing, and even doing this without the use of a “bigger” type. The idea is as follows: As usual, we parse digits left to right, and collect the resulting value in an accumulator `acc`, i.e., for each new digit `d`, the accumulator is updated to base * acc + d Nothing new up to here. However, before we start parsing, calculate (lim, m) = upper_bound `divMod` base and before updating the accumulator with another digit `d`, verify that acc < lim || (acc == lim && d <= m) which exactly guarantees that the accumulator will not overflow. The reason why this works is is easily seen by doing the example for `Word16` in base 10: > (maxBound :: Word16) `divMod` 10 (6553,5) > 10 * fst it + snd it 65535 Complexity: This adds a modulo operation and two comparisons for every literal being parsed, plus one comparison for every digit. In order to limit memory consumption, some comparison has to take place during parsing, at least for limiting the number of digits consumed. In total, this does not look too expensive. I have [implemented][4] this idea for `parsec` and `attoparsec` to demonstrate the idea (only for decimal values). What now? --------- Obviously, this *should not be a another library*, trying to fix some aspect of some other libraries. My code is rather intended for demonstration. I'd prefer to help this idea migrate to the libraries (`base`, `parsec`, `attoparsec`, …), where the correct parsers should be. Unfortunately, I got a bit lost when trying to track down the code of `read` in the `base` package. And I think I may have overengineered my solution for attoparsec to accommodate different stream types. Also, I get the impression that Haskell *library* code seems to be written with a different mindset, a deeper understanding of GHC than mine, i.e., more tailored to what the compiler will *actually do* when using the code, trying not to spoil opportunities for optimisation. And I'm not sure I'm up to that task. So I'm asking for feedback on the proposed algorithm, my implementation, and hints on where and how to get this into established libraries. Build instructions ================== $ cabal build $ cabal run demo $ cabal test $ cabal haddock [1]: https://hackage.haskell.org/package/base-4.21.0.0/docs/Prelude.html#v:read [2]: https://hackage.haskell.org/package/attoparsec-0.14.4/docs/Data-Attoparsec-… [3]: https://hackage.haskell.org/package/parsec-3.1.18.0/docs/Text-Parsec-Token.… [4]: https://github.com/s5k6/robust-int [5]: https://stackoverflow.com/questions/24171005/how-to-parse-an-integer-with-p… [6]: https://hackage.haskell.org/package/parsec3-numbers [7]: https://github.com/s5k6/robust-int/blob/master/src/Data/RobustInt/Parsec.hs… [8]: https://hackage.haskell.org/package/megaparsec-9.7.0/docs/Text-Megaparsec-C… -- Stefan Klinger, Ph.D. -- computer scientist o/X http://stefan-klinger.de /\/ https://github.com/s5k6 \ I prefer receiving plain text messages, not exceeding 32kB.

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TargirDotCom
by walid falcon 07 Aug '25

07 Aug '25

https://www.targir.com/ https://www.targir.com/2025/04/blog-post_14.html

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شهادة الأبوة في المغرب
by walid falcon 07 Aug '25

07 Aug '25

Spam detection software, running on the system "mail.haskell.org", has identified this incoming email as possible spam. The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see @@CONTACT_ADDRESS@@ for details. Content preview: ÙÙ ÙØ§ ØªØØªØ§Ø¬ ÙØ¹Ø±ÙØªÙ ØÙÙ Ø´ÙØ§Ø¯Ø© Ø§ÙØ£Ø¨ÙØ© Ø¨Ø§ÙÙØºØ±Ø¨ ÙÙÙÙÙ ØªØÙÙÙ Ø§ÙØ·ÙØ¨ ÙÙ Ø®ÙØ§Ù Ø§ÙØ±Ø§Ø¨Ø· Ø§ÙÙØ¨Ø§Ø´Ø± https://www.targir.com/2025/04/blog-post_14.html [...] Content analysis details: (6.6 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (pikolasikolatest2[at]gmail.com) -0.0 SPF_PASS SPF: sender matches SPF record 0.1 FREEMAIL_ENVFROM_END_DIGIT Envelope-from freemail username ends in digit (pikolasikolatest2[at]gmail.com) 5.0 UNWANTED_LANGUAGE_BODY BODY: Message written in an undesired language 0.0 HTML_MESSAGE BODY: HTML included in message 1.5 BODY_8BITS BODY: Body includes 8 consecutive 8-bit characters 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid 0.0 T_TO_NO_BRKTS_FREEMAIL T_TO_NO_BRKTS_FREEMAIL The original message was not completely plain text, and may be unsafe to open with some email clients; in particular, it may contain a virus, or confirm that your address can receive spam. If you wish to view it, it may be safer to save it to a file and open it with an editor.

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POPL 2026 Call For Tutorials
by Ningning Xie 06 Aug '25

06 Aug '25

POPL 2026 CALL FOR TUTORIALS https://popl26.sigplan.org/track/POPL-2026-tutorials#Call-For-Tutorials The 53rd ACM SIGPLAN Symposium on Principles of Programming Languages (POPL 2026) will be held in Rennes, France. 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. Tutorials for POPL 2026 are solicited on any topic relevant to the POPL community. We particularly encourage submissions of introductory tutorials that make the research presented at POPL more accessible to the participants. Tutorials will be held on Jan 11–13, 2026. The expected length of a tutorial is 3 hours, including questions and discussion (Q&A). Submission details Deadline for submission: October 10th, 2025 Notification of acceptance: October 24th, 2025 A tutorial proposal should provide the following information: - Tutorial title - Presenter(s), affiliation(s), and contact information - 1-3 page description (for evaluation). This should include the objectives, topics to be covered, presentation approach, target audience, prerequisite knowledge, and if the tutorial was previously held, the location (i.e. which conference), date, and number of attendees if available. - 1-2 paragraph abstract suitable for tutorial publicity. - 1-paragraph biography suitable for tutorial publicity. Proposals must be submitted by email to Robert Rand (rand(a)uchicago.edu) and Alan Schmitt (alan.schmitt(a)inria.fr) with the subject line "POPL 2026 Tutorial Proposal: [tutorial name]". The proposal should be attached as a PDF, docx, or txt file. Further information Any questions regarding POPL 2026 tutorials should be addressed to the workshops chairs, Robert Rand (rand(a)uchicago.edu) and Alan Schmitt (alan.schmitt(a)inria.fr)

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GHC 9.10.3-rc2 is now available
by Zubin Duggal 06 Aug '25

06 Aug '25

The GHC developers are very pleased to announce the availability of the second release candidate for GHC 9.10.3. Binary distributions, source distributions, and documentation are available at [downloads.haskell.org][] and via [GHCup](https://www.haskell.org/ghcup/). GHC 9.10.3 is a bug-fix release fixing over 50 issues of a variety of severities and scopes. A full accounting of these fixes can be found in the [release notes][]. As always, GHC's release status, including planned future releases, can be found on the GHC Wiki [status][]. The changes from the first release candidate are: - Bumping the text submodule to 2.1.3 - Reverting a bug fix (!14291) that restricted previously allowed namespace specifiers (#26250) - Reverting the bump of the deepseq submodule to 1.5.2.0 (#26251) This release candidate will have a two-week testing period. If all goes well the final release will be available the week of 19 August 2025. We would like to thank Well-Typed, Tweag I/O, Juspay, QBayLogic, Channable, Serokell, SimSpace, the 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. [release notes]: https://gitlab.haskell.org/ghc/ghc/-/blob/ghc-9.10/docs/users_guide/9.10.3-… [status]: https://gitlab.haskell.org/ghc/ghc/-/wikis/GHC-status [downloads.haskell.org] https://downloads.haskell.org/ghc/9.10.3-rc2 [ticket]: https://gitlab.haskell.org/ghc/ghc/-/issues/new

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ICFP 2025 (Co-Located with SPLASH!): Call for Participation
by ICFP Publicity 03 Aug '25

03 Aug '25

================================================== Call for Participation The 30th ACM SIGPLAN International Conference on Functional Programming (ICFP 2025) and affiliated events *** This year, co-located with SPLASH for a *** *** joint ICFP/SPLASH Conference *** https://icfp25.sigplan.org Singapore; Oct 12-18, 2025 *** Register by Aug 31, 2025 for a discount! *** ================================================== ICFP is a celebration of the art and science of functional programming, providing a forum for researchers and developers to engage on a variety of topics, from foundations to features, and from abstraction to application. This year, for the first time in history, ICFP will be co-located with SPLASH and its satellite events as a part of the joint ICFP/SPLASH 2025 conference. You are invited to participate in a full week of events dedicated to the art and science of programming, featuring both the ICFP and SPLASH main conferences as well as numerous related events. * ICFP Accepted Papers: https://icfp25.sigplan.org/track/icfp-2025-papers#event-overview * Registration: https://icfp25.sigplan.org/attending/registration *The early-bird deadline is August 31, 2025* (Additionally, there is a full week discount if you register for 7 days!) * Venue (Sunday Workshops only): NUS School of Computing https://icfp25.sigplan.org/venue/splash-2025-venue1 * Venue (Main Conference): Marina Bay Sands Convention Centre https://icfp25.sigplan.org/venue/splash-2025-venue Full list of events: October 12 Tutorials - https://conf.researchr.org/track/icfp-splash-2025/icfp-splash-2025-tutorials PLMW - https://conf.researchr.org/home/icfp-splash-2025/plmw-icfp-splash-2025 TyDE - https://conf.researchr.org/home/icfp-splash-2025/tyde-2025 FARM - https://2025.splashcon.org/track/splash-2025-farm HOPE - https://conf.researchr.org/home/icfp-splash-2025/hope-2025 Erlang - https://conf.researchr.org/home/icfp-splash-2025/erlang-2025 FUNARCH - https://conf.researchr.org/home/icfp-splash-2025/funarch-2025 October 13-15 ICFP (3 days) - https://icfp25.sigplan.org/ October 13-14 SAS (2 days) - https://2025.splashcon.org/home/sas-2025 October 13 SPLASH Doctoral Symposium - https://2025.splashcon.org/track/splash-2025-Doctoral-Symposium SCALA - https://conf.researchr.org/home/icfp-splash-2025/scala-2025 PROPL - https://conf.researchr.org/home/icfp-splash-2025/propl-2025 October 14-15 OlivierFest (2 days) - https://conf.researchr.org/home/icfp-splash-2025/olivierfest-2025 October 14 HATRA - https://conf.researchr.org/home/icfp-splash-2025/hatra-2025 MPLR - https://conf.researchr.org/home/icfp-splash-2025/mplr-2025 IWACO - https://conf.researchr.org/home/icfp-splash-2025/iwaco-2025 October 15 PAINT - https://conf.researchr.org/home/icfp-splash-2025/paint-2025 LMPL - https://conf.researchr.org/home/icfp-splash-2025/lmpl-2025 VMIL - https://conf.researchr.org/home/icfp-splash-2025/vmil-2025 October 16-18 OOPSLA (3 days) - https://2025.splashcon.org/track/OOPSLA ONWARD! (3 days) - https://2025.splashcon.org/track/splash-2025-Onward-papers October 16-17 HASKELL (2 days) - https://conf.researchr.org/home/icfp-splash-2025/haskellsymp-2025 October 16 ML Family - https://conf.researchr.org/home/icfp-splash-2025/mlsymposium-2025 SCHEME - https://conf.researchr.org/home/icfp-splash-2025/scheme-2025 WASM - https://conf.researchr.org/home/icfp-splash-2025/webassembly-ws-2025 October 17 OCAML - https://conf.researchr.org/home/icfp-splash-2025/ocaml-2025 MINI KANREN - https://conf.researchr.org/home/icfp-splash-2025/minikanren-2025 October 18 SPLASH-E - https://2025.splashcon.org/track/splash-2025-SPLASH-E REBASE - https://conf.researchr.org/home/icfp-splash-2025/rebase-2025 Industry Forum - https://conf.researchr.org/home/icfp-splash-2025/industry-forum-2025 ICFP 2025 will feature three keynotes: Ekaterina Komendantskaya: Proof-Carrying Neuro-Symbolic Code https://icfp25.sigplan.org/details/icfp-2025-icfp-keynotes/2/Proof-Carrying… Christos Dimoulas: The Rational Programmer, A Method for Investigating Programming Language Pragmatics https://icfp25.sigplan.org/details/icfp-2025-icfp-keynotes/3/The-Rational-P… Satnam Singh: Functional Programming for Hardware Design https://icfp25.sigplan.org/details/icfp-2025-icfp-keynotes/1/Functional-Pro… ICFP 2025 conference organizers: https://icfp25.sigplan.org/committee/icfp-2025-organizing-committee We hope to see you in Singapore in October. Don't forget to register by *August 31, 2025* for the early-bird discount! Additionally, there is a *full-week discount*: register for the whole 7 days and only pay for 6! https://icfp25.sigplan.org/attending/registration

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