downloads.haskell.org ### Index of /ghc/9.12.5-rc4/

As a test of sorts, Stack and its 200+ dependencies builds fine with GHC 9.12.5-rc4.

If you want to use GHC 9.12.5-rc4 with Stack: Add a `setup-info` dictionary to a configuration file with the applicable entry for your operating system. For example, on Windows or macOS/AArch64, a `stack.yaml`: snapshot: nightly-2026-11-03 # GHC 9.12.4 compiler: ghc-9.12.4.20261102 compiler-check: match-exact # Anticipating possible future RC releases # Only required before the GHC version has been installed: setup-info: ghc: windows64: 9.12.4.20261102: url: https://downloads.haskell.org/ghc/9.12.5-rc4/ghc-9.12.4.20261102-x86_64-unknown-mingw32.tar.xz # Can be extended with SHA protections etc: see https://docs.haskellstack.org/en/stable/configure/yaml/non-project/#setup-info macosx-aarch64: 9.12.4.20261102: url: https://downloads.haskell.org/ghc/9.12.5-rc4/ghc-9.12.4.20261102-aarch64-apple-darwin.tar.bz2 # Can be extended with SHA protections etc: see https://docs.haskellstack.org/en/stable/configure/yaml/non-project/#setup-info

Click to view the official SEC document.

GHC 9.14.2-rc2 is now available Announcements > 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 via GHCup. See also the previous announcement of 9.14.2-rc1. The changes since the first release candidate are: Several fixes to the specialiser and demand analyser for miscompilations causing incorrect runtime results, crashes, or hangs (#27626, #27627, #27629, #27703, #2… GHC 9.14.2-rc2 is now available > * Version 2 of the GHC Jobserver Protocol for GHC’s `-jsem` > jobserver on Linux and other POSIX platforms (#25087, #27253). This is sadly > a necessary breaking change: `-jsem` requires cabal-install 3.18 or later, > and is otherwise ignored with a warning, falling back to > sequential compilation. >

For the last three years I’ve been compiling a “breakage inventory” that documents all the breaking changes that accompany a GHC release. Since GHC 10 will be upon us in perhaps a month or two () I want to check whether this is this useful to anyone and, if so, whether anyone would like to help me compile it for GHC 10.

Is semaphore support fix going to be backported to 9.14 too?

Thanks for that reminder. It seems the way to do away with this confusion would be to rename it the /unit db/ and rename `ghc-pkg` to `ghc-unit(s)` . Units are arguably also not part of the Haskell language, but GHC needs to know about them to be able to link.

Agda also builds fine (500 modules, 130 deps)!

The GHC developers are pleased to announce the availability of the fourth release candidate for GHC 9.12.5, ghc-9.12.5-rc4. The fourth release candidate was necessary due to a large amount of critical issues that required backporting. This will be the last release candidate before release if no critical _regressions_ are discovered in this RC – we’re so far past due that we don’t backport anymore bugfixes for this release. Binary distributions, source distributions, and documentation are available at downloads.haskell.org and via GHCup. This release candidate will have a two-week testing period. If all goes well the final release will be available the week of November 17 2026. GHC 9.12.5 is a bug-fix release fixing many issues of a variety of severities and scopes, including: * Implement version 2 of the ghc `semaphore` protocol for GHC’s `-jsem` jobserver on Linux and other `POSIX` platforms (#25087, #27253) * several improvements to the pattern match checker (#25926, #27124) * several improvements to the demand analyser (#27261, #27106, #26416) * several fixes regarding the interaction of ticks and coercions (#27121, #26929, #26642, #26693) * several fixes for blackholes (#27261) … and many more Mind that the very important overhaul of the semaphore-compat library to v2 is included in this release and that the semaphore feature will only start working with cabal-install 3.18 again, which is sadly a breaking but necessary change. 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. GHC development is sponsored by: * Juspay * QBayLogic * Channable * Haskell Foundation * Serokell * Well-Typed * Tweag * Dotcom-Monitor * LoadView * Web Hosting Buddy * Find My Electric * Standard Chartered * UpCloud * Mercury 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.

I tested RC4 on current Stackage Nightly (building 3617 packages) and it was fine.

願わくばGhc now runs in your browser - Show and Tell - Haskell Communityで紹介されている、Wasm版GHCを使ったウェブアプリケーションとしてリリースしたい。Wasm版GHCが難しそうであれば、GHCi in the Browser - Vaibhav Sagarで紹介されている、containerを使ったバージョンでも良い。

Package qualified imports is a GHC specific extension, not part of any Language standard, IIRC.