- ghc-devs - Haskell.org

GitLab Account Approval
by DashiellWill 07 Nov '24

07 Nov '24

I'm looking to get my gitlab account approved. user name: dashiell

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giving a label to a thread
by Kazu Yamamoto 06 Nov '24

06 Nov '24

Hi all, GHC 9.6 provides listThreads. This is very useful to check thread leaks on network servers. Thanks. Users cannot label threads if fundamental functions fork threads without labelling. A good example is "timeout". If there are many threads without label, the debugging gets harder. So, I would like to ask to label threads in libraries shipped with GHC. --Kazu

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[ANNOUNCE] GHC 9.12.1-alpha1 is now available
by Zubin Duggal 05 Nov '24

05 Nov '24

The GHC developers are very pleased to announce the availability of the first alpha release of GHC 9.12.1. Binary distributions, source distributions, and documentation are available at [downloads.haskell.org][]. We hope to have this release available via ghcup shortly. GHC 9.12 will bring a number of new features and improvements, including: * The new language extension [OrPatterns] allowing you to combine multiple pattern clauses into one. * The [MultilineStrings] language extension to allow you to more easily write strings spanning multiple lines in your source code. * Improvements to the OverloadedRecordDot extension, allowing the built-in `HasField` class to be used for records with fields of non lifted representations. * The [NamedDefaults] language extension has been introduced allowing you to define defaults for typeclasses other than `Num`. * More deterministic object code output, controlled by the `-fobject-determinism` flag, which improves determinism of builds a lot (though does not fully do so) at the cost of some compiler performance (1-2%). See #12935 for the details * GHC now accepts type syntax in expressions as part of [GHC Proposal #281]. * ... and many more A full accounting of changes 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][]. We would like to thank GitHub, IOG, the Zw3rk stake pool, Well-Typed, Tweag I/O, Serokell, Equinix, 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://downloads.haskell.org/ghc/9.12.1-alpha1/docs/users_guide/9.12.1-not… [status]: https://gitlab.haskell.org/ghc/ghc/-/wikis/GHC-status [downloads.haskell.org] https://downloads.haskell.org/ghc/9.12.1-alpha1 [ticket]: https://gitlab.haskell.org/ghc/ghc/-/issues/new [OrPatterns]: https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0522-o… [MultilineStrings]: https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0569-m… [GHC Proposal #281]: https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0281-v… [NamedDefaults]: https://github.com/ghc-proposals/ghc-proposals/blob/master/proposals/0409-e… Cheers, Zubin

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Allow `base < 5` for package `array`
by Lei Zhu 04 Nov '24

04 Nov '24

Hi, I'm preparing the next `array` release for the coming ghc 9.12. The process seems boring because I just need to loosen the upper bound of the `base`, and then make a release. Shall I have a larger range like `base < 5` or are there any restriction in the `base`, so we have to bump the version one by one? Thanks, Lei Zhu

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Re: ghc-devs Digest, Vol 255, Issue 3
by Lei Zhu 03 Nov '24

03 Nov '24

Hi Zubin, I'll do the r2 release as you advised. Thanks, Lei Zhu On Sun, Nov 3, 2024 at 8:02 PM <ghc-devs-request(a)haskell.org> wrote: > Send ghc-devs mailing list submissions to > ghc-devs(a)haskell.org > > To subscribe or unsubscribe via the World Wide Web, visit > http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs > or, via email, send a message with subject or body 'help' to > ghc-devs-request(a)haskell.org > > You can reach the person managing the list at > ghc-devs-owner(a)haskell.org > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of ghc-devs digest..." > > > Today's Topics: > > 1. Allow `base < 5` for package `array` (Lei Zhu) > 2. Re: Allow `base < 5` for package `array` (Zubin Duggal) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Sun, 3 Nov 2024 16:37:09 +0800 > From: Lei Zhu <julytreee(a)gmail.com> > To: ghc-devs(a)haskell.org > Subject: Allow `base < 5` for package `array` > Message-ID: > <CAGfc3OtzHGKqN3-6RtwA2Q_iMHMQLZjd5= > mQQ80fGSON5R5eYg(a)mail.gmail.com> > Content-Type: text/plain; charset="utf-8" > > Hi, > > I'm preparing the next `array` release for the coming ghc 9.12. > The process seems boring because I just need to loosen the > upper bound of the `base`, and then make a release. > > Shall I have a larger range like `base < 5` or are there any > restriction in the `base`, so we have to bump the version > one by one? > > Thanks, > Lei Zhu >

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What makes C++ FFI painful?
by Hécate 01 Nov '24

01 Nov '24

Hi devs, Pardon me for the naïve question. I know that C++ FFI is *hard* in Haskell. From the perspective of an end-user I have heard that `text`'s new UTF-8 validation caused problems when released, as it relied on C++ code, but I never had any problems with it personally. From the GHC perspective, what makes C++ a difficult language to interface with? Cheers, Hécate -- Hécate ✨ 🐦: @TechnoEmpress IRC: Hecate WWW: https://glitchbra.in RUN: BSD

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9.12.1-alpha2 and submodule status
by Zubin Duggal 01 Nov '24

01 Nov '24

Hi all, I am currently in the process of preparing 9.12.1-alpha2. I expect a release to be published by the end of this week. We are tracking the current status of the submodules in this spreadsheet: https://docs.google.com/spreadsheets/d/19WeWjXPh8Q64qoe3fjs8AswpTHk6uLBD8WG… I want to finalise submodule versions by the next alpha in 2 weeks. If you have any requests for newer versions of submodules/boot libraries, please update the spreadsheet and drop me a message. Cheers, Zubin

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`getSizeofMutableByteArray#` may return a negative number
by Adithya Kumar 30 Oct '24

30 Oct '24

The following test is done with `ghc-9.6.6`. ``` {-# LANGUAGE UnboxedTuples #-} {-# LANGUAGE MagicHash #-} import GHC.Base (IO(..)) import GHC.Exts import Prelude hiding (length) data MutByteArray = MutByteArray (MutableByteArray# RealWorld) {-# INLINE new #-} new :: Int -> IO MutByteArray new (I# nbytes) = IO $ \s -> case newByteArray# nbytes s of (# s', mbarr# #) -> let c = MutByteArray mbarr# in (# s', c #) {-# INLINE length #-} length :: MutByteArray -> IO Int length (MutByteArray arr) = IO $ \s -> case getSizeofMutableByteArray# arr s of (# s1, i #) -> (# s1, I# i #) test1 :: IO () test1 = do val <- new (-7) len <- length val print len test2 :: IO () test2 = do val <- new (-8) len <- length val print len ``` `test1` succeeds and prints `-7` The test prints the length for all `>= -7` `test2` fails with `Out of memory` If `length <= -8`, the test fails with `Out of memory` This is an interesting quirk. I expected `newByteArray#` to fail if the size given to it is `< 0` and I never expected `getSizeofMutableByteArray#` would return a negative number. Best, Adithya

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Can't build GHC any more
by Simon Peyton Jones 24 Oct '24

24 Oct '24

Friends On all my builds, using ./boot; ./configure; ./hadrian/build I am getting the crash below. What should I do? My boot compiler is ghc-9.6. I can't build GHC at all right now, so this is somewhat urgent. Thank you! Simon ]0;Running for 5m11s [11771/39023], predicted 49s (86%)(/home/simonpj/code/HEAD) ]0;Running for 5m16s [11771/39023], predicted 49s (86%)(/home/simonpj/code/HEAD) ghc/GHCi/UI.hs:1704:5: warning: [GHC-53633] [-Woverlapping-patterns] Pattern match is redundant In a case alternative: _ -> ... | 1704 | _ -> pure () | ^^^^^^^^^^^^ | Run Ghc CompileHs (Stage0 InTreeLibs): ghc/Main.hs => _build/stage0/ghc/build/Main.o | Run Ghc LinkHs (Stage0 InTreeLibs): _build/stage0/ghc/build/Main.o (and 6 more) => _build/stage0/bin/ghc Command line: /home/simonpj/.ghcup/bin/ghc -Wall -Wcompat -hisuf hi -osuf o -hcsuf hc -static -hide-all-packages -no-user-package-db '-package-env -' '-package-db _build/stage0/lib/package.conf.d' '-this-unit-id ghc-bin-9.13.20241015-inplace' '-this-package-name ghc-bin' '-package-id array-0.5.5.0' '-package-id base-4.18.0.0' '-package-id bytestring-0.11.4.0' '-package-id containers-0.6.7' '-package-id deepseq-1.4.8.1' '-package-id directory-1.3.9.0-inplace' '-package-id exceptions-0.10.7' '-package-id filepath-1.5.2.0-inplace' '-package-id ghc-9.13-inplace' '-package-id ghc-boot-9.13-inplace' '-package-id ghc-prim-0.10.0' '-package-id ghci-9.13-inplace' '-package-id haskeline-0.8.2.1' '-package-id process-1.6.25.0-inplace' '-package-id time-1.14-inplace' '-package-id transformers-0.6.1.0' '-package-id unix-2.8.5.1-inplace' -i -i/home/simonpj/code/HEAD/_build/stage0/ghc/build -i/home/simonpj/code/HEAD/_build/stage0/ghc/build/ghc/autogen -i/home/simonpj/code/HEAD/ghc -I_build/stage0/ghc/build -I/home/simonpj/.ghcup/ghc/9.6.2/lib/ghc-9.6.2/lib/x86_64-linux-ghc-9.6.2/process-1.6.17.0/include -I/home/simonpj/code/HEAD/compiler -I/home/simonpj/code/HEAD/_build/stage0/compiler/build -I/home/simonpj/code/HEAD/libraries/process/include -I/home/simonpj/code/HEAD/_build/stage0/libraries/process/build/include -I/home/simonpj/code/HEAD/libraries/directory -I/home/simonpj/code/HEAD/_build/stage0/libraries/directory/build -I/home/simonpj/code/HEAD/libraries/unix/include -I/home/simonpj/code/HEAD/_build/stage0/libraries/unix/build/include -I/home/simonpj/code/HEAD/libraries/time/lib/include -I/home/simonpj/code/HEAD/_build/stage0/libraries/time/build/lib/include -I/home/simonpj/.ghcup/ghc/9.6.2/lib/ghc-9.6.2/lib/x86_64-linux-ghc-9.6.2/directory-1.3.8.1/include -I/home/simonpj/.ghcup/ghc/9.6.2/lib/ghc-9.6.2/lib/x86_64-linux-ghc-9.6.2/unix-2.8.1.0/include -I/home/simonpj/.ghcup/ghc/9.6.2/lib/ghc-9.6.2/lib/x86_64-linux-ghc-9.6.2/time-1.12.2/include -I/home/simonpj/.ghcup/ghc/9.6.2/lib/ghc-9.6.2/lib/x86_64-linux-ghc-9.6.2/bytestring-0.11.4.0/include -I/home/simonpj/.ghcup/ghc/9.6.2/lib/ghc-9.6.2/lib/x86_64-linux-ghc-9.6.2/base-4.18.0.0/include -I/home/simonpj/.ghcup/ghc/9.6.2/lib/ghc-9.6.2/lib/x86_64-linux-ghc-9.6.2/ghc-bignum-1.3/include -I/home/simonpj/.ghcup/ghc/9.6.2/lib/ghc-9.6.2/lib/x86_64-linux-ghc-9.6.2/rts-1.0.2/include -optP-include -optP_build/stage0/ghc/build/ghc/autogen/cabal_macros.h -optP-DHAVE_INTERNAL_INTERPRETER -outputdir _build/stage0/ghc/build -fdiagnostics-color=always -Wall -Wnoncanonical-monad-instances -Wnoncanonical-monoid-instances -rtsopts=all '-with-rtsopts=-K512M -H -I5 -T' -threaded -XGHC2021 -XNoImplicitPrelude -XScopedTypeVariables -XBangPatterns -no-auto-link-packages -rtsopts -optc-Wno-error=inline _build/stage0/ghc/build/Main.o _build/stage0/ghc/build/GHCi/Leak.o _build/stage0/ghc/build/GHCi/UI.o _build/stage0/ghc/build/GHCi/UI/Info.o _build/stage0/ghc/build/GHCi/UI/Monad.o _build/stage0/ghc/build/GHCi/UI/Exception.o _build/stage0/ghc/build/GHCi/Util.o -o _build/stage0/bin/ghc -O -H32m -dcore-lint -fomit-interface-pragmas -I_build/stage0/compiler/build -DDEBUG ===> Command failed with error code: 1 /usr/bin/ld.gold: error: _build/stage0/lib/../lib/x86_64-linux-ghc-9.6.2/unix-2.8.5.1-inplace/libHSunix-2.8.5.1-inplace.a(HsUnix.o): multiple definition of '__hsunix_rtldNext' /usr/bin/ld.gold: /home/simonpj/.ghcup/ghc/9.6.2/lib/ghc-9.6.2/lib/../lib/x86_64-linux-ghc-9.6.2/unix-2.8.1.0/libHSunix-2.8.1.0.a(HsUnix.o): previous definition here /usr/bin/ld.gold: error: _build/stage0/lib/../lib/x86_64-linux-ghc-9.6.2/unix-2.8.5.1-inplace/libHSunix-2.8.5.1-inplace.a(HsUnix.o): multiple definition of '__hsunix_rtldDefault' /usr/bin/ld.gold: /home/simonpj/.ghcup/ghc/9.6.2/lib/ghc-9.6.2/lib/../lib/x86_64-linux-ghc-9.6.2/unix-2.8.1.0/libHSunix-2.8.1.0.a(HsUnix.o): previous definition here /usr/bin/ld.gold: error: _build/stage0/lib/../lib/x86_64-linux-ghc-9.6.2/unix-2.8.5.1-inplace/libHSunix-2.8.5.1-inplace.a(HsUnix.o): multiple definition of '__hsunix_push_module' /usr/bin/ld.gold: /home/simonpj/.ghcup/ghc/9.6.2/lib/ghc-9.6.2/lib/../lib/x86_64-linux-ghc-9.6.2/unix-2.8.1.0/libHSunix-2.8.1.0.a(HsUnix.o): previous definition here /usr/bin/ld.gold: error: _build/stage0/lib/../lib/x86_64-linux-ghc-9.6.2/unix-2.8.5.1-inplace/libHSunix-2.8.5.1-inplace.a(HsUnix.o): multiple definition of '__hsunix_clocks_per_second' /usr/bin/ld.gold: /home/simonpj/.ghcup/ghc/9.6.2/lib/ghc-9.6.2/lib/../lib/x86_64-linux-ghc-9.6.2/unix-2.8.1.0/libHSunix-2.8.1.0.a(HsUnix.o): previous definition here /usr/bin/ld.gold: error: _build/stage0/lib/../lib/x86_64-linux-ghc-9.6.2/unix-2.8.5.1-inplace/libHSunix-2.8.5.1-inplace.a(HsUnix.o): multiple definition of '__hscore_readdir' /usr/bin/ld.gold: /home/simonpj/.ghcup/ghc/9.6.2/lib/ghc-9.6.2/lib/../lib/x86_64-linux-ghc-9.6.2/unix-2.8.1.0/libHSunix-2.8.1.0.a(HsUnix.o): previous definition here /usr/bin/ld.gold: error: _build/stage0/lib/../lib/x86_64-linux-ghc-9.6.2/unix-2.8.5.1-inplace/libHSunix-2.8.5.1-inplace.a(HsUnix.o): multiple definition of '__hscore_d_name' /usr/bin/ld.gold: /home/simonpj/.ghcup/ghc/9.6.2/lib/ghc-9.6.2/lib/../lib/x86_64-linux-ghc-9.6.2/unix-2.8.1.0/libHSunix-2.8.1.0.a(HsUnix.o): previous definition here /usr/bin/ld.gold: error: _build/stage0/lib/../lib/x86_64-linux-ghc-9.6.2/unix-2.8.5.1-inplace/libHSunix-2.8.5.1-inplace.a(HsUnix.o): multiple definition of '__hscore_free_dirent' /usr/bin/ld.gold: /home/simonpj/.ghcup/ghc/9.6.2/lib/ghc-9.6.2/lib/../lib/x86_64-linux-ghc-9.6.2/unix-2.8.1.0/libHSunix-2.8.1.0.a(HsUnix.o): previous definition here collect2: error: ld returned 1 exit status `gcc' failed in phase `Linker'. (Exit code: 1) ]0;Finished in 5m19s(/home/simonpj/code/HEAD) Command failed Build failed. make: *** [/home/simonpj/code/Makefile-spj:12: all] Error 1 simonpj@LHR-WD-22561:~/code/HEAD$

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How is ExitCode handled?
by Tom Ellis 21 Oct '24

21 Oct '24

Hello all, I'm not sure I understand how an `ExitCode` exception is used to terminate a running program. Can anyone clarify? When we call `exitWith`, what we're doing is `throw`ing an `ExitCode` exception: https://www.stackage.org/haddock/lts-22.38/base-4.18.2.1/src/System.Exit.ht… That exception must be caught somewhere, and used to cause the running program to exit with the exit code in question. But where? It's not in the default `uncaughtExceptionHandler`: https://hackage.haskell.org/package/base-4.20.0.0/docs/src/GHC-Conc-Sync.ht… That doesn't do anything special with exit code. It seems like real_handler does: https://hackage.haskell.org/package/ghc-internal-9.1001.0/docs/src/GHC.Inte… >From my experiements with a small program (below) I conclude that the default handler is installed on every thread, and real_handler is installed *on the main thread only* *below* the default handler, so that if an `ExitCode` exception is thrown the default handler never gets a chance to see it. Is that right? Thanks, Tom {-# LANGUAGE GHC2021 #-} {-# LANGUAGE LambdaCase #-} import System.Environment (getArgs) import System.Exit (ExitCode (ExitFailure)) import Control.Exception (Exception, SomeException (SomeException), throw) import GHC.Conc (forkIO, setUncaughtExceptionHandler, threadDelay) data MyEx = MyEx deriving Show instance Exception MyEx myHandler (SomeException e) = putStrLn $ "In myHandler: " <> show e run f = do setUncaughtExceptionHandler myHandler f main = do getArgs >>= \case -- Exits with exit code 1 ["1"] -> run (throw (ExitFailure 1)) -- Print: In myHandler: MyEx -- Exits with exit code 1 ["2"] -> run (throw MyEx) -- Print: In myHandler: ExitFailure 1 -- Exits with exit code 0 ["3"] -> run (forkIO (throw (ExitFailure 1))) -- Print: In myHandler: MyEx -- Exits with exit code 0 ["4"] -> run (forkIO (throw MyEx)) _ -> error "Need an argument" threadDelay (1000 * 1000)

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