- Glasgow-haskell-users

[ANNOUNCE] GHC 8.8.1 is now available
by Ben Gamari 06 Sep '19

06 Sep '19

Hello everyone, The GHC team is pleased to announce the release candidate for GHC 8.8.1. The source distribution, binary distributions, and documentation are available at https://downloads.haskell.org/ghc/8.8.1 This release is the culmination of over 3000 commits by over one hundred contributors and has several new features and numerous bug fixes relative to GHC 8.6: * Visible kind applications are now supported (GHC Proposal #15) * Profiling now works correctly on 64-bit Windows (although still may be problematic on 32-bit Windows due to platform limitations; see #15934) * A new code layout algorithm for amd64's native code generator significantly improving the runtime performance of some kernels * The introduction of a late lambda-lifting pass which may reduce allocations significantly for some programs. * Further work on Trees That Grow, enabling improved code re-use of the Haskell AST in tooling * Users can write `forall` in more contexts (GHC Proposal #7) * The pattern-match checker is now more precise in the presence of strict fields with uninhabited types. * A comprehensive audit of GHC's memory ordering barriers has been performed, resulting in a number of fixes that should significantly improve the reliability of programs on architectures with weakly-ordered memory models (e.g. PowerPC, many ARM and AArch64 implementations). * A long-standing linker limitation rendering GHCi unusable with projects with cyclic symbol dependencies has been fixed (#13786) * Further work on the Hadrian build system * Countless miscellaneous bug-fixes Unfortunately, due to a build issue (#17108) found late in the release process i386 Windows builds are currently unavailable. These will be provided in the coming weeks. As always, if anything looks amiss do let us know. Happy compiling! Cheers, - Ben [1] https://downloads.haskell.org/ghc/8.8.1/docs/html/users_guide/8.8.1-notes.h…

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exhausted simplifier ticks and hs-boot files
by Ganesh Sittampalam 30 Aug '19

30 Aug '19

Hi, The code below (also attached - unzip and run go.sh) triggers the GHC panic "Simplifier ticks exhausted", and I'm unsure whether I should view it as an instance of the known infelicity in the inliner (https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/bugs.html#b…) My code does have a recursive datatype, but the recursion isn't contravariant, which is the case described in "Secrets of the GHC inliner" (https://www.microsoft.com/en-us/research/wp-content/uploads/2002/07/inline.…, section 4). It's cut down from some real code where I have a mutually recursive datatype that I want to define across two modules for code structuring reasons, meaning I need a .hs-boot file. I haven't been able to reproduce it without the .hs-boot file - if I put everything in one module it stops happening. I've tried with a range of GHC versions from 8.2.x to an early version of 8.8. It happens with -O1 and not -O0, but I haven't managed to find a specific optimisation that triggers it. Is this just an instance of the known problem in a different guise, or is it something different and worth a bug report? Cheers, Ganesh T2.hs-boot ----------- module T2 where data T2 mapP_T2 :: (Int -> Int) -> T2 -> T2 T1.hs ----- module T1 where import {-# SOURCE #-} T2 data T1 = T1 T2 mapP_T1 :: (Int -> Int) -> T1 -> T1 mapP_T1 _ (T1 xs) = T1 (mapP_T2 id xs) T2.hs ----- module T2 where import T1 data T2 = T2 T1 mapP_T2 :: (Int -> Int) -> T2 -> T2 mapP_T2 f (T2 t) = T2 (mapP_T1 f t) go :: T1 -> T1 go = mapP_T1 id GHC output ---------- $ ghc --make T2.hs -O1 -fsimpl-tick-factor=1000 -ddump-simpl-stats) [...] ghc.exe: panic! (the 'impossible' happened) (GHC version 8.2.2 for x86_64-unknown-mingw32): Simplifier ticks exhausted When trying UnfoldingDone mapP_T2 To increase the limit, use -fsimpl-tick-factor=N (default 100) If you need to do this, let GHC HQ know, and what factor you needed Total ticks: 61203 24481 PreInlineUnconditionally 6121 ds_i17h 6120 f_a16p 6120 ds_d17d 6120 ds1_i17i 12241 UnfoldingDone 6121 mapP_T1 6120 mapP_T2 24481 BetaReduction 6121 ds_i17h 6120 f_a16p 6120 ds_d17d 6120 ds1_i17i

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`StablePtr` in `ST`
by Matthew Farkas-Dyck 21 Aug '19

21 Aug '19

I have been doing some work where i want `StablePtr`, but also to not be confined to `IO`. I saw the following comment in "compiler/prelude/PrimOp.hs": Question: Why @RealWorld@ - won't any instance of @_ST@ do the job? [ADR] It has been there for 20 years. What is the answer? If it is safe i'll send the patch generalizing these operations.

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[ANNOUNCE] GHC 8.8.1 release candidate 1 is now available
by Ben Gamari 22 Jul '19

22 Jul '19

Hello everyone, The GHC team is pleased to announce the release candidate for GHC 8.8.1. The source distribution, binary distributions, and documentation are available at https://downloads.haskell.org/ghc/8.8.1-rc1 This release is the culmination of over 3000 commits by over one hundred contributors and has several new features and numerous bug fixes relative to GHC 8.6: * Profiling now works correctly on 64-bit Windows (although still may be problematic on 32-bit Windows due to platform limitations; see #15934) * A new code layout algorithm for amd64's native code generator * The introduction of a late lambda-lifting pass which may reduce allocations significantly for some programs. * Further work on Trees That Grow, enabling improved code re-use of the Haskell AST in tooling * More locations where users can write `forall` (GHC Proposal #0007) * A comprehensive audit of GHC's memory ordering barriers has been performed, resulting in a number of fixes that should significantly improve the reliability of programs on architectures with weakly-ordered memory models (e.g. PowerPC, many ARM and AArch64 implementations). * A long-standing linker limitation rendering GHCi unusable with projects with cyclic symbol dependencies has been fixed (#13786) * Further work on the Hadrian build system * Numerous bug-fixes As always, if anything looks amiss do let us know. Happy compiling! Cheers, - Ben [1] https://downloads.haskell.org/ghc/8.8.1-rc1/docs/html/users_guide/8.8.1-not…

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The future of the SPARC NCG backend
by Ben Gamari 27 Jun '19

27 Jun '19

Hello everyone, If you use (or think you might use in the future) GHC's SPARC NCG backend please do leave a note on #16882 [1]. My impression is that it has no users and no plausible means of testing. Consequently I am suggesting that we remove it in GHC 8.12. Cheers, - Ben [1] https://gitlab.haskell.org/ghc/ghc/issues/16882

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[ANNOUNCE] GHC 8.8.1-alpha2 is now available
by Ben Gamari 22 Jun '19

22 Jun '19

Hello everyone, The GHC team is pleased to announce the second and likely last alpha release of GHC 8.8.1. The source distribution, binary distributions, and documentation are available at https://downloads.haskell.org/~ghc/8.8.1-alpha2 A draft of the release notes is also available [1]. This release is the culmination of over 3000 commits by over one hundred contributors and has several new features and numerous bug fixes relative to GHC 8.6: * Profiling now works correctly on 64-bit Windows (although still may be problematic on 32-bit Windows due to platform limitations; see #15934) * A new code layout algorithm for amd64's native code generator * The introduction of a late lambda-lifting pass which may reduce allocations significantly for some programs. * Further work on Trees That Grow, enabling improved code re-use of the Haskell AST in tooling * More locations where users can write `forall` (GHC Proposal #0007) * Further work on the Hadrian build system This release brings a number of fixes since alpha 1: * A number of linker fixes (#16779, #16784) * The process, binary, Cabal, time, terminfo libraries have all been bumped to their final release versions * A regression rendering TemplateHaskell unusable in cross-compiled configurations has been fixed (#16331) * A regression causing compiler panics on compilation of some programs has been fixed (#16449) * -Wmissing-home-modules now handles hs-boot files correctly (#16551) * A regression causing some programs to fail at runtime has been fixed (#16066) Due to on-going work on our release and testing infrastructure this cycle is proceeding at a pace significantly slower than expected. However, we anticipate that this investment will allow us to release a more reliable, easier-to-install compiler on the planned six-month release cadence in the future. As always, if anything looks amiss do let us know. Happy compiling! Cheers, - Ben [1] https://downloads.haskell.org/ghc/8.8.1-alpha2/docs/html/users_guide/8.8.1-…

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Re: [ANNOUNCE] GHC 8.8.1-alpha2 is now available
by Ben Gamari 17 Jun '19

17 Jun '19

That is true and this will be fixed for the release candidate. However Debian 8 is now no longer Debian's current stable release so I wasn't prioritizing this issue. If the lack of a Debian 8 distribution is preventing anyone from testing please let me know. Cheers, - Ben On June 17, 2019 6:24:16 AM EDT, Matthew Pickering <matthewtpickering(a)gmail.com> wrote: >There seems to be no debian8 bindist which is different from every >release at least back to ghc-8.0.1. > >On Sat, Jun 15, 2019 at 8:36 PM Ben Gamari <ben(a)well-typed.com> wrote: >> >> Hello everyone, >> >> The GHC team is pleased to announce the second and likely last alpha >> release of GHC 8.8.1. The source distribution, binary distributions, >and >> documentation are available at >> >> https://downloads.haskell.org/~ghc/8.8.1-alpha2 >> >> A draft of the release notes is also available [1]. >> >> This release is the culmination of over 3000 commits by over one >hundred >> contributors and has several new features and numerous bug fixes >> relative to GHC 8.6: >> >> * Profiling now works correctly on 64-bit Windows (although still >may >> be problematic on 32-bit Windows due to platform limitations; see >> #15934) >> >> * A new code layout algorithm for amd64's native code generator >> >> * The introduction of a late lambda-lifting pass which may reduce >> allocations significantly for some programs. >> >> * Further work on Trees That Grow, enabling improved code re-use of >the >> Haskell AST in tooling >> >> * More locations where users can write `forall` (GHC Proposal #0007) >> >> * Further work on the Hadrian build system >> >> This release brings a number of fixes since alpha 1: >> >> * A number of linker fixes (#16779, #16784) >> >> * The process, binary, Cabal, time, terminfo libraries have all been >> bumped to their final release versions >> >> * A regression rendering TemplateHaskell unusable in cross-compiled >> configurations has been fixed (#16331) >> >> * A regression causing compiler panics on compilation of some >programs >> has been fixed (#16449) >> >> * -Wmissing-home-modules now handles hs-boot files correctly >(#16551) >> >> * A regression causing some programs to fail at runtime has been >fixed >> (#16066) >> >> Due to on-going work on our release and testing infrastructure this >> cycle is proceeding at a pace significantly slower than expected. >> However, we anticipate that this investment will allow us to release >a >> more reliable, easier-to-install compiler on the planned six-month >> release cadence in the future. >> >> As always, if anything looks amiss do let us know. >> >> Happy compiling! >> >> Cheers, >> >> - Ben >> >> [1] >https://downloads.haskell.org/ghc/8.8.1-alpha2/docs/html/users_guide/8.8.1-… >> _______________________________________________ >> ghc-devs mailing list >> ghc-devs(a)haskell.org >> http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs -- Sent from my Android device with K-9 Mail. Please excuse my brevity.

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Typed hole improvements
by David Feuer 07 Jun '19

07 Jun '19

I've been playing around with 8.6.3, and I've really been appreciating the improvements in typed hole messages. Both the information about constraints and the suggestions for filling the holes have proven valuable in heavily typish programming. Thanks! One thing that's still not where I'd like it to be is the equality constraint display. I recognize this is a Hard Problem. But digging through something like x ~ C y z x ~ C y1 z2 D p b ~ q z y1 to get b ~ y gets tiresome. Is there room for improvement here? If not, are there any programs around using the GHC API to offer an interactive system for such calculations? It'd be quite helpful when seeing such constraints to be able to express special interest in a particular type variable, for example.

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[ANNOUNCE] GHC 8.6.5 is now available
by Ben Gamari 03 May '19

03 May '19

Hello everyone, The GHC team is proud to announce the release of GHC 8.6.5. The source distribution, binary distributions, and documentation are available at https://downloads.haskell.org/~ghc/8.6.5 Release notes are also available [1]. This release fixes a handful of issues with 8.6.4: - Binary distributions once again ship with Haddock documentation including syntax highlighted source of core libraries (#16445) - A build system issue where use of GCC with `-flto` broke `configure` was fixed (#16440) - An bug affecting Windows platforms wherein XMM register values could be mangled when entering STG has been fixed (#16514) - Several Windows packaging issues resulting from the recent CI rework. (#16408, #16398, #16516) Do note that due to linking issues (see #15934) profiling will be rather unreliable on Windows. This will be fixed in 8.8.1. As always, if anything looks amiss do let us know. Happy compiling! Cheers, - Ben [1] http://downloads.haskell.org/~ghc/8.6.5/docs/html/users_guide/8.6.5-notes.h…

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[ANNOUNCE] GHC 8.8.1-alpha1 is now available
by Ben Gamari 26 Apr '19

26 Apr '19

Hello everyone, The GHC team is pleased to announce the first alpha release of GHC 8.8.1. The source distribution, binary distributions, and documentation are available at https://downloads.haskell.org/~ghc/8.8.1-alpha1 A draft of the release notes is also available [1]. This release is the culmination of over 3000 commits by over one hundred contributors and has several new features and numerous bug fixes relative to GHC 8.6: * Profiling now works correctly on 64-bit Windows (although still may be problematic on 32-bit Windows due to platform limitations; see #15934) * A new code layout algorithm for amd64's native code generator * The introduction of a late lambda-lifting pass which may reduce allocations significantly for some programs. * Further work on Trees That Grow, enabling improved code re-use of the Haskell AST in tooling * More locations where users can write `forall` (GHC Proposal #0007) * Further work on the Hadrian build system This release starts the pre-release cycle for GHC 8.8. This cycle is starting quite a bit later than expected due recent work on GHC's CI and release infrastructure. See the GHC Blog [2] for more on this. As always, if anything looks amiss do let us know. Happy compiling! Cheers, - Ben [1] https://downloads.haskell.org/ghc/8.8.1-alpha1/docs/html/users_guide/8.8.1-… [2] https://www.haskell.org/ghc/blog/20190405-ghc-8.8-status.html

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