July 2026 - Haskell-Cafe

The Leksah (Haskell) IDE for Windows, Linux & macOS
by Andrew Goh 14 Aug '26

14 Aug '26

Dear Haskell Cafe, There was the Leksah (Haskell) IDE about 10 to 12 years ago. I wonder if you chaps can bring it back for the Windows, Linux and maybe macOS platform. I have the GHCup toolchain installed after a few mistries, and set up VS Code for Haskell programming, but I still would really prefer the Leksah IDE (this time in native mode) instead. As for the macOS platform, there is a Haskell Mac for IDE that can be brought for under US$10. Lastly, why don't you allow Haskell users to subscribe to all Haskell mailing lists rather than go individaully to each one to do that. - Andrew

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GHC 9.14.2-rc1 is now available
by Zubin Duggal 31 Jul '26

31 Jul '26

The GHC developers are very pleased to announce the availability of the release candidate for GHC 9.14.2. Binary distributions, source distributions, and documentation are available at [downloads.haskell.org][] and via [GHCup](https://www.haskell.org/ghcup/). GHC 9.14.2 is a bug-fix release fixing many issues of a variety of severities and scopes, including: * Fixed a CorePrep miscompilation that could project a field out of an absent dictionary, resulting in a segfault (#25924) * Fixed demand analysis giving an absent demand to an argument that was still used by the function's stable unfolding, which could cause a run-time crash (#26416) * Numerous fixes for register allocation and Cmm register-conflict analysis bugs, preventing incorrect code generation and corruption of vector registers when spilling and reloading (#26411, #26526, #26537, #26542, #26550, #26668) * Many NGG fixes on AArch64: `MOVK` clobbering live values (#26980), register clobbering and an incorrect overflow bit in `MUL2` (#27046, #27047), and incorrect sign extension (#26978) and unsigned right shift (#26979) at sub-word widths * Fixed several black hole handling bugs that could lead to deadlocks or crashes in multithreaded programs, showing up as hangs or "END_TSO_QUEUE object entered" errors (#26922, #26936) * Fixed a stack alignment bug on x86 that could cause segfaults or corrupted registers when using AVX/AVX-512 vector code (#26595, #26822) * Fixed an "unknown/strange object" crash in the compacting garbage collector (#27434) * Fixed a regression that caused overloaded functions to no longer be specialised as effectively as in previous releases, hurting runtime performance (#26831) * Fixed exponential-time desugaring of nested `case` expressions (#27383, #20251) * Fixes for several compiler panics, including issues with SetLevels (#26681), the type-class specialiser (#26682), `mkTick` (#26772, #27121) and CoreToStg (#27182, #27386) * Fixed cast worker/wrapper incorrectly firing on INLINE functions (#26903) * Fixed negative type literals causing the compiler to hang (#26861) * Fixed associated type family and data family instance changes not triggering recompilation (#26183, #26705) * Improvements to determinism of compiler output, including the order in which `:info` lists instances (#26846, #26858, #26877, #27532) * Fixed split sections support on Windows (#26696, #26494) and the LLVM backend (#26770) * The JavaScript backend now supports more than 128 registers, fixing runtime `ReferenceError` failures for functions taking very many arguments (#26558) * Fixes for the Wasm backend, and the RISC-V and PowerPC native code generators * ... and many more 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][]. This release candidate will have a two-week testing period. If all goes well the final release will be available the week of 13 August 2026. GHC development is sponsored by: * [Juspay](https://juspay.com/) * [QBayLogic](https://qbaylogic.com/) * [Channable](https://www.channable.com/) * [Haskell Foundation](https://haskell.foundation/) * [Serokell](https://serokell.io/) * [Well-Typed](https://well-typed.com/) * [Tweag](https://www.tweag.io/) * [Dotcom-Monitor](https://www.dotcom-monitor.com/) * [LoadView](https://www.loadview-testing.com/) * [Web Hosting Buddy](https://webhostingbuddy.com/) * [Find My Electric](https://www.findmyelectric.com/) * [Standard Chartered](https://www.sc.com) * [UpCloud](https://upcloud.com) * [Mercury](https://mercury.com) We would like to thank these sponsors 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-9.14/docs/users_guide/9.14.2-… [status]: https://gitlab.haskell.org/ghc/ghc/-/wikis/GHC-status [downloads.haskell.org] https://downloads.haskell.org/ghc/9.14.2-rc1 [ticket]: https://gitlab.haskell.org/ghc/ghc/-/issues/new

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2026 Haskell Workshop Videos Now Online
by Dominik Schrempf 25 Jul '26

25 Jul '26

Dear haskell-cafe! We are happy to announce that the recordings from this year’s Haskell Implementors’ Workshop and Haskell Ecosystem Workshop are now available online. Both workshops were held on the lakeside campus of the University of Applied Sciences of Eastern Switzerland (OST) in Rapperswil on June 4th and 5th, alongside ZuriHac, and hosted by the Haskell Foundation. https://haskell.foundation/news/2026-07-18/hiw-hew-2026-videos.html Dominik

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LibreOffice gets LAMBDA expression
by Henning Thielemann 18 Jul '26

18 Jul '26

Simon Peyton Jones advocated for LAMBDA in Excel for long. Now we also get it in LibreOffice: https://gerrit.libreoffice.org/c/core/+/206265

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ICFP'26: Call for Participation and Early Registration Discount until July 25
by ICFP Publicity 17 Jul '26

17 Jul '26

ICFP'26: Call for Participation and Early Registration Reminder The 31st ACM SIGPLAN International Conference on Functional Programming (ICFP 2026) and affiliated events invite you to participate in a full week dedicated to functional programming! https://icfp26.sigplan.org Indianapolis, Indiana, USA; Aug 24-29, 2026 Early Registration Open Until July 25 *Register here*: https://icfp26.sigplan.org/attending/registration *Early registration discount* is available until *July 25*! ICFP Overview 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. - Accepted Papers: https://icfp26.sigplan.org/track/icfp-2026-icfp-papers - Registration: https://icfp26.sigplan.org/attending/registration (Early registration discount available until *July 25*!) - Venue: Indiana University Indianapolis https://icfp26.sigplan.org/venue/icfp-2026-venue1 - Hotel Blocks: https://icfp26.sigplan.org/attending/hotel-blocks - Tutorials: https://icfp26.sigplan.org/track/icfp-2026-icfp-tutorials Keynotes Keynote speakers this year: - Edward Lee (UC Berkeley): "Deterministic Concurrency" - Lindsey Kuper (UC Santa Cruz): "Interpreters everywhere!" - Daan Leijen (Microsoft Research): "Efficient strong functional programming with effects and compiler guided reference counting" More info: https://icfp26.sigplan.org/track/icfp-2026-icfp-keynotes Co-Located Events There are several events co-located with ICFP: *Monday, August 24* - PLMW: https://icfp26.sigplan.org/home/PLMW-ICFP-2026 - HOPE: https://icfp26.sigplan.org/home/hope-2026 - miniKanren: https://icfp26.sigplan.org/home/minikanren-2026 - FARM: https://icfp26.sigplan.org/home/farm-2026 *Tuesday-Thursday, August 25-27* - ICFP - Main conference *Friday, August 28* - Haskell (Aug 28-29): https://icfp26.sigplan.org/home/haskellsymp-2026 - Erlang: https://icfp26.sigplan.org/home/erlang-2026 - ML Family: https://icfp26.sigplan.org/home/mlfamilyworkshop-2026 - LOPSTR+PPDP (Aug 27-29): https://icfp26.sigplan.org/home/lopstr-ppdp-2026 *Saturday, August 29* - Haskell (Aug 28-29): https://icfp26.sigplan.org/home/haskellsymp-2026 - Scheme: https://icfp26.sigplan.org/home/scheme-2026 - FUNARCH: https://icfp26.sigplan.org/home/funarch-2026 - LOPSTR+PPDP (Aug 27-29): https://icfp26.sigplan.org/home/lopstr-ppdp-2026

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POPL 2027 Last Call for Papers
by Ningning Xie 08 Jul '26

08 Jul '26

POPL 2027 Call for Papers Sun 10 - Sat 16 January 2027 Mexico City, Mexico https://popl27.sigplan.org/ ============================= PACMPL Issue POPL 2027 seeks contributions on all aspects of programming languages and programming systems, both theoretical and practical. Authors of papers published in PACMPL Issue POPL 2027 will be invited – but not required – to present their work in the POPL conference in January 2027, which is sponsored by ACM SIGPLAN, in cooperation with ACM SIGACT and ACM SIGLOG. **NEW FOR 2027** - Clarification about expectations concerning mechanized proofs; see Submission Guidelines: https://popl27.sigplan.org/track/POPL-2027-popl-research-papers#submission-… - At least one author of each paper submission must be registered as a Reserve Reviewer as per the Reserve Reviewer Policy: https://popl27.sigplan.org/track/POPL-2027-popl-research-papers#reserve-rev… See details: https://popl27.sigplan.org/track/POPL-2027-popl-research-papers ## Important Dates - Paper submission deadline: Thursday July 9, 2026 - Author response period: Mon 7 - Thu 10 Sep, 2026 - Author notification: Mon 5 Oct, 2026 - Revision deadline: Mon 26 Oct, 2026 - Final acceptance notification: Mon 9 Nov, 2026 - Camera ready deadline: Fri 20 Nov, 2026 ## Submission Site Information The submission site is https://popl27.hotcrp.com. Papers may be resubmitted to the submission site multiple times up until the deadline, but only the last version submitted before the deadline will be reviewed. There is no abstract deadline. The submission site requires entering author names and affiliations, relevant topics, and potential conflicts. Addition or removal of authors after the submission deadline will need to be approved by the Program Chair (as this kind of change potentially undermines the goal of eliminating conflicts during paper assignment). The submission deadline is 11:59PM July 9, 2026 anywhere on earth: https://en.wikipedia.org/wiki/Anywhere_on_Earth ## Scope Principles of Programming Languages (POPL) is a forum for the discussion of all aspects of programming languages and programming systems. Both theoretical and experimental papers are welcome, on topics ranging from formal frameworks to experience reports. We seek submissions that make principled, enduring contributions to the theory, design, understanding, implementation, or application of programming languages. ## Evaluation Criteria The Review Committee (aka Program Committee, PC) will evaluate the technical contribution of each submission as well as its accessibility to both experts and the general POPL audience. All papers will be judged on significance, originality, relevance, correctness, and clarity. Each paper must explain its scientific contribution in both general and technical terms, identifying what has been accomplished, explaining why it is significant and comparing it with previous work. Advice on writing technical papers can be found on the SIGPLAN author information page (https://www.sigplan.org/Resources/Author/) ## Double-Blind Reviewing POPL 2027 will use a full double-blind reviewing process (similar to the one used in recent years (POPL 2023 - 2026) but different from the lightweight double-blind process used before then). This means that identities of authors will not be made visible to reviewers until after conditional-acceptance decisions have been made, and then only for the conditionally-accepted papers. ## Important update on ACM’s new open access publishing model for ACM Conferences Starting January 1, 2026, ACM has fully transitioned to Open Access. All ACM publications, including those from ACM-sponsored conferences, will be 100% Open Access. Authors will have two primary options for publishing Open Access articles with ACM: the ACM Open institutional model or by paying Article Processing Charges (APCs). For a paper to be covered by ACM Open, the corresponding author must be affiliated with a participating institution. APC pricing for 2027 conferences is currently under review and will be finalized in June. With over 2,600 institutions already part of ACM Open, the majority of ACM-sponsored conference papers will not require APCs from authors or conferences. Authors from institutions not participating in ACM Open will need to pay an APC to publish their papers, unless they qualify for a waiver. To find out whether an APC applies to your article, please consult the list of participating institutions (https://libraries.acm.org/acmopen/open-participants) in ACM Open and review the APC Waivers and Discounts Policy ( https://www.acm.org/publications/policies/policy-on-open-access-apc-waivers… ).

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Wiki account creation
by Brandon Chinn 06 Jul '26

06 Jul '26

I sent an email to wiki-account-request(a)haskell.org about adding a Haskell Wiki account for me under `brandonchinn178`, but I'm not seeing any references to that mailing list at https://mailman.haskell.org/mailman3/lists/, so I'm copying to this mailing list in case that list is inactive. Thanks, Brandon Chinn

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bug in ghci module loading post 9.12.4?
by Evan Laforge 03 Jul '26

03 Jul '26

I recently upgraded from ghc 9.2 to 9.6 (I know, I'm slow), and one of the things I was looking forward to was better recompilation avoidance, that wouldn't be fooled by spurious mtime changes that are common with with e.g. git branch switches. Unfortunately, it seems to have gotten buggy at the same time! I upgraded again to 9.12.4 and it looks like it's still buggy. Either that or I'm doing things wrong somehow. Here's a repro, it requires 3 modules: % cat >BugA.hs module BugA where x :: Int x = 13 % cat >BugB.hs module BugB where import qualified BugA f :: IO () f = print BugA.x % cat >BugC.hs module BugC where import qualified BugB bug :: IO () bug = BugB.f % ghci -fobject-code # compile so we can load .o GHCi, version 9.12.4: https://www.haskell.org/ghc/ :? for help Loaded GHCi configuration from /Users/elaforge/qlib/dotfiles/.ghci Prelude> :load BugC [1 of 3] Compiling BugA ( BugA.hs, BugA.o ) [2 of 3] Compiling BugB ( BugB.hs, BugB.o ) [3 of 3] Compiling BugC ( BugC.hs, BugC.o ) Ok, three modules loaded. Leaving GHCi. % ghci Prelude> :load BugC Ok, three modules loaded. Prelude BugC> bug 13 As expected! Now go edit BugA.hs, and change 13 to say 14, and save. Now reload: Prelude BugC> :r [1 of 3] Compiling BugA ( BugA.hs, interpreted ) [Source file changed] Ok, three modules reloaded. Prelude BugC> bug 13 So that's not right! This will also cause linking errors if something was removed, though it's easier to reproduce the stale values. For my interpretation of what's going on, I believe previously it would have also reloaded BugB. While it has noticed that BugA must be reloaded (and switched to bytecode), it hasn't noticed that BugB is in the dependency path and should also be reloaded, and possibly winds up using stale values inlined into BugB.o. Is it a bug?

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