# Latest

**URL:** https://discourse.haskell.org/latest.md

[Latest](https://discourse.haskell.org/latest.md) · [Categories](https://discourse.haskell.org/categories.md) · [Tags](https://discourse.haskell.org/tags.md)

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## [Welcome to the Haskell Discourse!](https://discourse.haskell.org/t/welcome-to-the-haskell-discourse/7)

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**Author:** [@system](https://discourse.haskell.org/u/system)\
**Replies:** 0\
**Last updated:** [February 16, 2019, 11:18am UTC](https://discourse.haskell.org/t/welcome-to-the-haskell-discourse/7 "2019-02-16T11:18:56Z")

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About this forum Haskell is a statically typed, pure, functional programming language. Any discussion about Haskell is welcome on this forum. In particular the following topics are encouraged: Announcements about new …

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## [The wasted potential of Haskell: Language & Compiler](https://discourse.haskell.org/t/the-wasted-potential-of-haskell-language-compiler/14743)

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**Author:** [@mastarija](https://discourse.haskell.org/u/mastarija)\
**Replies:** 30\
**Last updated:** [September 27, 2026, 1:49pm UTC](https://discourse.haskell.org/t/the-wasted-potential-of-haskell-language-compiler/14743 "2026-09-27T13:49:06Z")

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This quite resonates with me at the moment, so I’m interested to hear other’s opinions. A common insult hurled at Haskell is that it’s a “committee language”. My take is that this was not the case initial…

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## [How to check multiline case?](https://discourse.haskell.org/t/how-to-check-multiline-case/14755)

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**Author:** [@raiko](https://discourse.haskell.org/u/raiko)\
**Replies:** 5\
**Last updated:** [September 27, 2026, 9:22am UTC](https://discourse.haskell.org/t/how-to-check-multiline-case/14755 "2026-09-27T09:22:49Z")

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Hi everyone! I’m new to Haskell and I started from Haskell MOOC. Now I’m in lecture 3 exercises and wondering how to solve that one: -- Ex 7: implement a functional while loop. While should be a function -- that takes …

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## [Differences between \`foldl\` and \`foldr\`](https://discourse.haskell.org/t/differences-between-foldl-and-foldr/14744)

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**Author:** [@Kleidukos](https://discourse.haskell.org/u/Kleidukos)\
**Replies:** 6\
**Last updated:** [September 27, 2026, 3:46am UTC](https://discourse.haskell.org/t/differences-between-foldl-and-foldr/14744 "2026-09-27T03:46:19Z")

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This article is a reproduction of a seminal explanation by Alexis King of the differences between foldr and foldl, both strict and lazy versions. As it has been used consistently to teach newcomers since its first appea…

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## [Strict extension unexpectedly forcing lazy record field assignment](https://discourse.haskell.org/t/strict-extension-unexpectedly-forcing-lazy-record-field-assignment/14748)

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**Author:** [@moll](https://discourse.haskell.org/u/moll)\
**Replies:** 3\
**Last updated:** [September 26, 2026, 7:25pm UTC](https://discourse.haskell.org/t/strict-extension-unexpectedly-forcing-lazy-record-field-assignment/14748 "2026-09-26T19:25:18Z")

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Hey, I’m not sure if it’s me, a bug or just an unexpected outcome when record updating desugaring was changed, but I’m seeing a lazy record field being forced when updating it under the Strict extension. It’s not forced…

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## [Rust-style Attribute Macro in Haskell, using GHC 10 Modifiers Extension](https://discourse.haskell.org/t/rust-style-attribute-macro-in-haskell-using-ghc-10-modifiers-extension/14726)

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**Author:** [@konn](https://discourse.haskell.org/u/konn)\
**Replies:** 10\
**Last updated:** [September 26, 2026, 12:31pm UTC](https://discourse.haskell.org/t/rust-style-attribute-macro-in-haskell-using-ghc-10-modifiers-extension/14726 "2026-09-26T12:31:07Z")

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As a long-time Haskeller writing Rust in production, I always miss the powerful Template Haskell macros - Rust’s macro system is rather ad-hoc and weaker than Haskell (it fails to handle hygienity properly, and, cruciall…

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## [Perspec 1.0 - A Haskell desktop app for perspective correction of document photos](https://discourse.haskell.org/t/perspec-1-0-a-haskell-desktop-app-for-perspective-correction-of-document-photos/14473)

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**Author:** [@ad-si](https://discourse.haskell.org/u/ad-si)\
**Replies:** 4\
**Last updated:** [September 26, 2026, 12:04pm UTC](https://discourse.haskell.org/t/perspec-1-0-a-haskell-desktop-app-for-perspective-correction-of-document-photos/14473 "2026-09-26T12:04:53Z")

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After 9 years of on-and-off development, I’m happy to announce the 1.0 release of Perspec, a desktop app for correcting the perspective of photos of documents, receipts, and whiteboards. The headline feature of 1.0 is a…

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## [Can't compile unix-2.8.8.0 on AARCH64](https://discourse.haskell.org/t/cant-compile-unix-2-8-8-0-on-aarch64/14740)

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**Author:** [@lmcyber](https://discourse.haskell.org/u/lmcyber)\
**Replies:** 5\
**Last updated:** [September 26, 2026, 7:37am UTC](https://discourse.haskell.org/t/cant-compile-unix-2-8-8-0-on-aarch64/14740 "2026-09-26T07:37:04Z")

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I tried to compile a stack project on alpine 3.24 using a raspberry pi 4. Nonetheless, I could compile the same project successfully on an intel 64 bit computer. Here are my specs: LTS 24.60 GHC 9.10.3 During the comp…

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## [The Hazy Haskell Compiler](https://discourse.haskell.org/t/the-hazy-haskell-compiler/13497)

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**Author:** [@superstar64](https://discourse.haskell.org/u/superstar64)\
**Replies:** 34\
**Last updated:** [September 26, 2026, 5:23am UTC](https://discourse.haskell.org/t/the-hazy-haskell-compiler/13497 "2026-09-26T05:23:09Z")

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I’m proud to showcase Hazy, my Haskell compiler. This is a project I have been working on in private for 3 years. It’s unfortunately not finished but it’s at the point where it’s fairly interesting. The type checker larg…

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## [Moggi - a kind of strict version of Haskell running on JVM, .NET & PHP](https://discourse.haskell.org/t/moggi-a-kind-of-strict-version-of-haskell-running-on-jvm-net-php/14725)

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**Author:** [@prolic](https://discourse.haskell.org/u/prolic)\
**Replies:** 4\
**Last updated:** [September 26, 2026, 12:57am UTC](https://discourse.haskell.org/t/moggi-a-kind-of-strict-version-of-haskell-running-on-jvm-net-php/14725 "2026-09-26T00:57:09Z")

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Moggi 0.1.0-alpha is released today. Moggi is a statically typed, purely functional programming language with strict evaluation. It has algebraic data types, GADTs, pattern matching, type classes, type inference, Gene…

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## [How to keep enjoying programming in a world of LLMs](https://discourse.haskell.org/t/how-to-keep-enjoying-programming-in-a-world-of-llms/14705)

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**Author:** [@turion](https://discourse.haskell.org/u/turion)\
**Replies:** 12\
**Last updated:** [September 25, 2026, 3:26pm UTC](https://discourse.haskell.org/t/how-to-keep-enjoying-programming-in-a-world-of-llms/14705 "2026-09-25T15:26:00Z")

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Are you steering towards AI burnout? Afraid of loosing your job to someone with little programming skills, no aspirations to quality, and a huge Claude account? Disappointed about the code quality in your projects, or wo…

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## [Writing Parquet Files Using Haskell](https://discourse.haskell.org/t/writing-parquet-files-using-haskell/14722)

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**Author:** [@mchav](https://discourse.haskell.org/u/mchav)\
**Replies:** 6\
**Last updated:** [September 25, 2026, 6:00am UTC](https://discourse.haskell.org/t/writing-parquet-files-using-haskell/14722 "2026-09-25T06:00:17Z")

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## [\[Well-Typed Blog\] Haskell ecosystem activities report: June–August 2026](https://discourse.haskell.org/t/well-typed-blog-haskell-ecosystem-activities-report-june-august-2026/14707)

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**Author:** [@adamgundry](https://discourse.haskell.org/u/adamgundry)\
**Replies:** 11\
**Last updated:** [September 24, 2026, 6:02pm UTC](https://discourse.haskell.org/t/well-typed-blog-haskell-ecosystem-activities-report-june-august-2026/14707 "2026-09-24T18:02:47Z")

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… and a question to the community: do you find these reports useful? What would you like to see more or less about?

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## [\[Well-Typed Blog\] Real-Time Telemetry with Eventlog Live](https://discourse.haskell.org/t/well-typed-blog-real-time-telemetry-with-eventlog-live/14738)

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**Author:** [@adamgundry](https://discourse.haskell.org/u/adamgundry)\
**Replies:** 3\
**Last updated:** [September 24, 2026, 4:10pm UTC](https://discourse.haskell.org/t/well-typed-blog-real-time-telemetry-with-eventlog-live/14738 "2026-09-24T16:10:09Z")

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## [Save the Dates: Haskell Ecosystem and Implementors' Workshops 2027](https://discourse.haskell.org/t/save-the-dates-haskell-ecosystem-and-implementors-workshops-2027/14736)

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**Author:** [@LaurentRDC](https://discourse.haskell.org/u/LaurentRDC)\
**Replies:** 0\
**Last updated:** [September 24, 2026, 2:28pm UTC](https://discourse.haskell.org/t/save-the-dates-haskell-ecosystem-and-implementors-workshops-2027/14736 "2026-09-24T14:28:09Z")

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The Haskell Foundation is happy to announce that its two ZuriHac prelude events, the Haskell Ecosystem Workshop and Haskell Implementors’ Workshop, will be coming back in 2027. Details at the link below.

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## [Issue 543 :: Haskell Weekly newsletter](https://discourse.haskell.org/t/issue-543-haskell-weekly-newsletter/14734)

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**Author:** [@taylorfausak](https://discourse.haskell.org/u/taylorfausak)\
**Replies:** 0\
**Last updated:** [September 24, 2026, 12:13pm UTC](https://discourse.haskell.org/t/issue-543-haskell-weekly-newsletter/14734 "2026-09-24T12:13:09Z")

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## [Https://github.com/haskell-actions/run-ormolu archived?](https://discourse.haskell.org/t/https-github-com-haskell-actions-run-ormolu-archived/14724)

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**Author:** [@arybczak](https://discourse.haskell.org/u/arybczak)\
**Replies:** 5\
**Last updated:** [September 24, 2026, 11:00am UTC](https://discourse.haskell.org/t/https-github-com-haskell-actions-run-ormolu-archived/14724 "2026-09-24T11:00:01Z")

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I can’t see anywhere why. Anyone knows?

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## [Does writing in a "beautiful" programming language still matter in the age of AI?](https://discourse.haskell.org/t/does-writing-in-a-beautiful-programming-language-still-matter-in-the-age-of-ai/14677)

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**Author:** [@pantapix](https://discourse.haskell.org/u/pantapix)\
**Replies:** 14\
**Last updated:** [September 23, 2026, 9:48pm UTC](https://discourse.haskell.org/t/does-writing-in-a-beautiful-programming-language-still-matter-in-the-age-of-ai/14677 "2026-09-23T21:48:16Z")

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We’ve repeatedly moved to higher levels of abstraction: from assembly to C and C++, then to languages and managed environments such as Java and C#. The lower layers didn’t become useless, but fewer developers needed to w…

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## [Tooling improvement // Integrate test watcher (cabal)](https://discourse.haskell.org/t/tooling-improvement-integrate-test-watcher-cabal/14623)

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**Author:** [@benjaminweb](https://discourse.haskell.org/u/benjaminweb)\
**Replies:** 30\
**Last updated:** [September 22, 2026, 6:56pm UTC](https://discourse.haskell.org/t/tooling-improvement-integrate-test-watcher-cabal/14623 "2026-09-22T18:56:00Z")

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From a developer’s perspective one of those basics I need is a watcher that reloads rapidly on any change I make on the code base and reruns all the tests. I dare to say it’s standard for many to develop in such a fashio…

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## [Why can (Cons i (q i)) -\> (Cons o (q o)) have an arrow instance, but not \[i\] -\> \[o\]](https://discourse.haskell.org/t/why-can-cons-i-q-i-cons-o-q-o-have-an-arrow-instance-but-not-i-o/14721)

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**Author:** [@fp.monkey](https://discourse.haskell.org/u/fp.monkey)\
**Replies:** 1\
**Last updated:** [September 22, 2026, 1:37pm UTC](https://discourse.haskell.org/t/why-can-cons-i-q-i-cons-o-q-o-have-an-arrow-instance-but-not-i-o/14721 "2026-09-22T13:37:20Z")

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I’m reading Arrows and Computation by Ross Paterson (2003), and in it he has a couple exercises where you need to produce Arrow instances for peculiar types (in fact, in 2026 you also need to make a Category instance to …

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## [Rel8 1.8 released!](https://discourse.haskell.org/t/rel8-1-8-released/14697)

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**Author:** [@TeofilC](https://discourse.haskell.org/u/TeofilC)\
**Replies:** 2\
**Last updated:** [September 22, 2026, 7:42am UTC](https://discourse.haskell.org/t/rel8-1-8-released/14697 "2026-09-22T07:42:32Z")

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Hi folks! We’re happy to announce the release of Rel8 1.8 ! :partying\_face: Rel8 is a Haskell library for interacting with PostgreSQL databases, built on top of the fantastic Opaleye library. The main objectives of Rel…

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## [London Haskell Meetup - September](https://discourse.haskell.org/t/london-haskell-meetup-september/14568)

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**Author:** [@L0neGamer](https://discourse.haskell.org/u/L0neGamer)\
**Replies:** 2\
**Last updated:** [September 21, 2026, 7:20pm UTC](https://discourse.haskell.org/t/london-haskell-meetup-september/14568 "2026-09-21T19:20:50Z")

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Calling all Londoners (and people who can get to London)! On Thursday 17th of September, we will be running a pair of talks at the Permutive offices. If you’re interested, sign up to the event! The Talks Learn to Rel8 …

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## [Vienna Haskell Meetup](https://discourse.haskell.org/t/vienna-haskell-meetup/11179)

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**Author:** [@fendor](https://discourse.haskell.org/u/fendor)\
**Replies:** 32\
**Last updated:** [September 21, 2026, 9:37am UTC](https://discourse.haskell.org/t/vienna-haskell-meetup/11179 "2026-09-21T09:37:03Z")

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Hello everyone! Due to the success of the last meetups, we are making the Vienna Haskell Meetup a regular occurrence, happening once every couple months. We are hosting the next Haskell meetup in Vienna on the 30th of …

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## [Helsinki Haskell Meetup, October 22](https://discourse.haskell.org/t/helsinki-haskell-meetup-october-22/14716)

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**Author:** [@chreekat](https://discourse.haskell.org/u/chreekat)\
**Replies:** 0\
**Last updated:** [September 21, 2026, 7:17am UTC](https://discourse.haskell.org/t/helsinki-haskell-meetup-october-22/14716 "2026-09-21T07:17:40Z")

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(The group still has a Meetup.com presence, but we are slowly moving to a Finland-based Mobilizon instance called Järkkää.)

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## [2026-06-09: Informal GHC Release Status Update of a Sort](https://discourse.haskell.org/t/2026-06-09-informal-ghc-release-status-update-of-a-sort/14250)

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**Author:** [@AndreasPK](https://discourse.haskell.org/u/AndreasPK)\
**Replies:** 5\
**Last updated:** [September 20, 2026, 11:04pm UTC](https://discourse.haskell.org/t/2026-06-09-informal-ghc-release-status-update-of-a-sort/14250 "2026-09-20T23:04:09Z")

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Hello Community! At ZuriHac I was encouraged to reach out more about what is going with GHC Releases. So this is a short and somewhat informal update about the status of various releases. Branches, branches everywhere …

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## [GHC 10.0.1-alpha1 is now available](https://discourse.haskell.org/t/ghc-10-0-1-alpha1-is-now-available/14706)

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**Author:** [@wz1000](https://discourse.haskell.org/u/wz1000)\
**Replies:** 9\
**Last updated:** [September 20, 2026, 7:06pm UTC](https://discourse.haskell.org/t/ghc-10-0-1-alpha1-is-now-available/14706 "2026-09-20T19:06:50Z")

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The GHC developers are very pleased to announce the availability of the first alpha prerelease of GHC 10.0.1. Binary distributions, source distributions, and documentation are available at downloads.haskell.org and vi…

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## [Lask — a task runner with its own typed language, written in Haskell](https://discourse.haskell.org/t/lask-a-task-runner-with-its-own-typed-language-written-in-haskell/14713)

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**Author:** [@torudev](https://discourse.haskell.org/u/torudev)\
**Replies:** 0\
**Last updated:** [September 20, 2026, 10:05am UTC](https://discourse.haskell.org/t/lask-a-task-runner-with-its-own-typed-language-written-in-haskell/14713 "2026-09-20T10:05:06Z")

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This is my first post here, and I’m afraid it’s about my own project — I hope that’s an acceptable way to introduce myself. What I made Lask is a task runner. It replaces Makefiles and CI YAML with a small typed languag…

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## [\[ANN\] pure-borrow-0.1.0.0](https://discourse.haskell.org/t/ann-pure-borrow-0-1-0-0/14712)

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**Author:** [@konn](https://discourse.haskell.org/u/konn)\
**Replies:** 0\
**Last updated:** [September 20, 2026, 9:05am UTC](https://discourse.haskell.org/t/ann-pure-borrow-0-1-0-0/14712 "2026-09-20T09:05:25Z")

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We are pleased to announce the release of pure-borrow-0.1.0.0 :tada: This is the second major release of Pure Borrow implementation, including the following changes: Breaking change: Alias now won’t take lifetime itse…

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## [GHC 9.14.2-rc2 is now available](https://discourse.haskell.org/t/ghc-9-14-2-rc2-is-now-available/14700)

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**Author:** [@wz1000](https://discourse.haskell.org/u/wz1000)\
**Replies:** 2\
**Last updated:** [September 19, 2026, 12:56pm UTC](https://discourse.haskell.org/t/ghc-9-14-2-rc2-is-now-available/14700 "2026-09-19T12:56:55Z")

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The GHC developers are very pleased to announce the availability of the second release candidate for GHC 9.14.2. Binary distributions, source distributions, and documentation are available at downloads.haskell.org and …

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## [Announcing: Little Haskell Compiler v0.1.0 pre-release - Try it online!](https://discourse.haskell.org/t/announcing-little-haskell-compiler-v0-1-0-pre-release-try-it-online/14702)

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**Author:** [@ApothecaLabs](https://discourse.haskell.org/u/ApothecaLabs)\
**Replies:** 13\
**Last updated:** [September 18, 2026, 6:59pm UTC](https://discourse.haskell.org/t/announcing-little-haskell-compiler-v0-1-0-pre-release-try-it-online/14702 "2026-09-18T18:59:00Z")

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I am pleased to announce the (pre) release of v0.1.0 of the Little Haskell Compiler, or LHC for short. The Little Haskell Compiler is a lightweight functional virtual machine based on Peter Landin’s SECD machine, which …

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