November 2015 - ghc-devs

A GHC Library
by Richard Eisenberg 08 Dec '15

08 Dec '15

Hi devs, It has struck me that we have a vast trove of documentation about GHC in the form of academic papers, but little organization to this trove. The papers are scattered across authors' websites, and sometimes it is hard to remember what a paper is titled when searching for it. I have thus started a wiki page here: https://ghc.haskell.org/trac/ghc/wiki/Library I would love for this page to be the Definitive List of GHC-related papers. The list I've included is, of course, woefully short, but it is a starting point. Please add to it! Have you written a GHC paper? If so, make sure it's included. Thanks, Richard

6 12

[ANNOUNCE] 7.10.3 release candidate 2
by Ben Gamari 07 Dec '15

07 Dec '15

Hello everyone, We are pleased to announce the second release candidate for GHC 7.10.3: https://downloads.haskell.org/~ghc/7.10.3-rc2/ This release differs from -rc1 by only two commits, * Disable the newly-introduced readelf configure check on non-ELF platforms. * Remove some tracing output from the typechecker that was causing some testsuites to fail. At the moment you should find the source tarball as well as 32- and 64-bit modern Linux (built on Debian 8) binary distributions available at the above URL. Windows and CentOS binaries will be made available shortly. As usual, you may need to work around our content delivery network's update latency by adding redundant forward-slashes to the URL. As far as OS X support goes, we are still looking for contributors to help us to support their platform by offering access to hardware, testing, or builds. Please let us know if you would be willing to provide any of the above. Happy testing! Cheers, - Ben

7 22

Plugins: How to determine ghc vs ghci
by Levent Erkok 04 Dec '15

04 Dec '15

I'm working on a plugin, and would like to be able to tell if it's GHC or GHCi that's running. I tried: df <- getDynFlags let isGHCi = ghcMode df == CompManager Alas, while that correctly tells apart "ghci" from "ghc -c", it also returns True when ghc is called without the "-c" argument. Is there a better/more robust way of figuring out whether we're in an interactive session? -Levent.

4 5

Bad interface file
by Simon Peyton Jones 03 Dec '15

03 Dec '15

Can anyone confirm that Trac #11122 is fixed in HEAD? When I try to reproduce it, I tried this, with a freshly-built HEAD cabal install parsec --with-ghc=/home/simonpj/5builds/HEAD-5/inplace/bin/ghc-stage2 But that fails as below, with a bizarre “bad interface file” error. Does anyone have a clue about what’s happening? Does it work for you? Simon cabal install parsec --with-ghc=/home/simonpj/5builds/HEAD-5/inplace/bin/ghc-stage2 Resolving dependencies... Configuring mtl-2.2.1... Building mtl-2.2.1... Preprocessing library mtl-2.2.1... [ 1 of 22] Compiling Control.Monad.Writer.Class ( Control/Monad/Writer/Class.hs, dist/build/Control/Monad/Writer/Class.o ) [ 2 of 22] Compiling Control.Monad.State.Class ( Control/Monad/State/Class.hs, dist/build/Control/Monad/State/Class.o ) [ 3 of 22] Compiling Control.Monad.Reader.Class ( Control/Monad/Reader/Class.hs, dist/build/Control/Monad/Reader/Class.o ) [ 4 of 22] Compiling Control.Monad.RWS.Class ( Control/Monad/RWS/Class.hs, dist/build/Control/Monad/RWS/Class.o ) [ 5 of 22] Compiling Control.Monad.Identity ( Control/Monad/Identity.hs, dist/build/Control/Monad/Identity.o ) [ 6 of 22] Compiling Control.Monad.Error.Class ( Control/Monad/Error/Class.hs, dist/build/Control/Monad/Error/Class.o ) [ 7 of 22] Compiling Control.Monad.Cont.Class ( Control/Monad/Cont/Class.hs, dist/build/Control/Monad/Cont/Class.o ) [ 8 of 22] Compiling Control.Monad.Trans ( Control/Monad/Trans.hs, dist/build/Control/Monad/Trans.o ) [ 9 of 22] Compiling Control.Monad.Error ( Control/Monad/Error.hs, dist/build/Control/Monad/Error.o ) [10 of 22] Compiling Control.Monad.Except ( Control/Monad/Except.hs, dist/build/Control/Monad/Except.o ) [11 of 22] Compiling Control.Monad.List ( Control/Monad/List.hs, dist/build/Control/Monad/List.o ) [12 of 22] Compiling Control.Monad.RWS.Lazy ( Control/Monad/RWS/Lazy.hs, dist/build/Control/Monad/RWS/Lazy.o ) [13 of 22] Compiling Control.Monad.RWS ( Control/Monad/RWS.hs, dist/build/Control/Monad/RWS.o ) [14 of 22] Compiling Control.Monad.Reader ( Control/Monad/Reader.hs, dist/build/Control/Monad/Reader.o ) [15 of 22] Compiling Control.Monad.RWS.Strict ( Control/Monad/RWS/Strict.hs, dist/build/Control/Monad/RWS/Strict.o ) [16 of 22] Compiling Control.Monad.State.Lazy ( Control/Monad/State/Lazy.hs, dist/build/Control/Monad/State/Lazy.o ) [17 of 22] Compiling Control.Monad.State ( Control/Monad/State.hs, dist/build/Control/Monad/State.o ) [18 of 22] Compiling Control.Monad.State.Strict ( Control/Monad/State/Strict.hs, dist/build/Control/Monad/State/Strict.o ) [19 of 22] Compiling Control.Monad.Writer.Lazy ( Control/Monad/Writer/Lazy.hs, dist/build/Control/Monad/Writer/Lazy.o ) [20 of 22] Compiling Control.Monad.Writer ( Control/Monad/Writer.hs, dist/build/Control/Monad/Writer.o ) [21 of 22] Compiling Control.Monad.Writer.Strict ( Control/Monad/Writer/Strict.hs, dist/build/Control/Monad/Writer/Strict.o ) [22 of 22] Compiling Control.Monad.Cont ( Control/Monad/Cont.hs, dist/build/Control/Monad/Cont.o ) In-place registering mtl-2.2.1... Creating package registration file: /tmp/pkgConf-mtl-2.253500.1 Installing library in /home/simonpj/.cabal/lib/x86_64-linux-ghc-7.11.20151125/mtl_29yPYQfz4VvKtYIFBb0Wdp Registering mtl-2.2.1... Installed mtl-2.2.1 Downloading text-1.2.1.3... Failed to install text-1.2.1.3 cabal: Error: some packages failed to install: parsec-3.1.9 depends on text-1.2.1.3 which failed to install. text-1.2.1.3 failed while downloading the package. The exception was: <socket: 10>: hGetBufSome: resource vanished (Connection reset by peer) simonpj@cam-05-unx:~/5builds/HEAD-5$ cabal install parsec --with-ghc=/home/simonpj/5builds/HEAD-5/inplace/bin/ghc-stage2 Resolving dependencies... Downloading text-1.2.1.3... Configuring text-1.2.1.3... Building text-1.2.1.3... Preprocessing library text-1.2.1.3... [ 1 of 44] Compiling Data.Text.Internal.Read ( Data/Text/Internal/Read.hs, dist/build/Data/Text/Internal/Read.o ) [ 2 of 44] Compiling Data.Text.Internal.Encoding.Utf32 ( Data/Text/Internal/Encoding/Utf32.hs, dist/build/Data/Text/Internal/Encoding/Utf32.o ) [ 3 of 44] Compiling Data.Text.Internal.Builder.RealFloat.Functions ( Data/Text/Internal/Builder/RealFloat/Functions.hs, dist/build/Data/Text/Internal/Builder/RealFloat/Functions.o ) [ 4 of 44] Compiling Data.Text.Internal.Builder.Int.Digits ( Data/Text/Internal/Builder/Int/Digits.hs, dist/build/Data/Text/Internal/Builder/Int/Digits.o ) [ 5 of 44] Compiling Data.Text.Encoding.Error ( Data/Text/Encoding/Error.hs, dist/build/Data/Text/Encoding/Error.o ) Data/Text/Encoding/Error.hs:3:14: warning: ‘Data.Text.Encoding.Error’ is marked as Trustworthy but has been inferred as safe! [ 6 of 44] Compiling Data.Text.Internal.Unsafe.Shift ( Data/Text/Internal/Unsafe/Shift.hs, dist/build/Data/Text/Internal/Unsafe/Shift.o ) [ 7 of 44] Compiling Data.Text.Internal.Encoding.Utf16 ( Data/Text/Internal/Encoding/Utf16.hs, dist/build/Data/Text/Internal/Encoding/Utf16.o ) [ 8 of 44] Compiling Data.Text.Internal.Functions ( Data/Text/Internal/Functions.hs, dist/build/Data/Text/Internal/Functions.o ) [ 9 of 44] Compiling Data.Text.Internal.Unsafe ( Data/Text/Internal/Unsafe.hs, dist/build/Data/Text/Internal/Unsafe.o ) [10 of 44] Compiling Data.Text.Array ( Data/Text/Array.hs, dist/build/Data/Text/Array.o ) [11 of 44] Compiling Data.Text.Internal.Unsafe.Char ( Data/Text/Internal/Unsafe/Char.hs, dist/build/Data/Text/Internal/Unsafe/Char.o ) [12 of 44] Compiling Data.Text.Internal ( Data/Text/Internal.hs, dist/build/Data/Text/Internal.o ) [13 of 44] Compiling Data.Text.Internal.Fusion.Size ( Data/Text/Internal/Fusion/Size.hs, dist/build/Data/Text/Internal/Fusion/Size.o ) [14 of 44] Compiling Data.Text.Internal.Fusion.Types ( Data/Text/Internal/Fusion/Types.hs, dist/build/Data/Text/Internal/Fusion/Types.o ) [15 of 44] Compiling Data.Text.Internal.Fusion.CaseMapping ( Data/Text/Internal/Fusion/CaseMapping.hs, dist/build/Data/Text/Internal/Fusion/CaseMapping.o ) [16 of 44] Compiling Data.Text.Internal.Fusion.Common ( Data/Text/Internal/Fusion/Common.hs, dist/build/Data/Text/Internal/Fusion/Common.o ) [17 of 44] Compiling Data.Text.Unsafe ( Data/Text/Unsafe.hs, dist/build/Data/Text/Unsafe.o ) [18 of 44] Compiling Data.Text.Internal.Private ( Data/Text/Internal/Private.hs, dist/build/Data/Text/Internal/Private.o ) [19 of 44] Compiling Data.Text.Internal.Fusion ( Data/Text/Internal/Fusion.hs, dist/build/Data/Text/Internal/Fusion.o ) [20 of 44] Compiling Data.Text.Show ( Data/Text/Show.hs, dist/build/Data/Text/Show.o ) Data/Text/Show.hs:57:11: warning: Rule "TEXT literal UTF8" may never fire because ‘unpackCStringUtf8#’ might inline first Probable fix: add an INLINE[n] or NOINLINE[n] pragma for ‘unpackCStringUtf8#’ [21 of 44] Compiling Data.Text.Internal.Encoding.Fusion.Common ( Data/Text/Internal/Encoding/Fusion/Common.hs, dist/build/Data/Text/Internal/Encoding/Fusion/Common.o ) [22 of 44] Compiling Data.Text.Internal.Encoding.Utf8 ( Data/Text/Internal/Encoding/Utf8.hs, dist/build/Data/Text/Internal/Encoding/Utf8.o ) [23 of 44] Compiling Data.Text.Internal.Encoding.Fusion ( Data/Text/Internal/Encoding/Fusion.hs, dist/build/Data/Text/Internal/Encoding/Fusion.o ) [24 of 44] Compiling Data.Text.Encoding ( Data/Text/Encoding.hs, dist/build/Data/Text/Encoding.o ) [25 of 44] Compiling Data.Text.Internal.Lazy.Encoding.Fusion ( Data/Text/Internal/Lazy/Encoding/Fusion.hs, dist/build/Data/Text/Internal/Lazy/Encoding/Fusion.o ) [26 of 44] Compiling Data.Text.Internal.Search ( Data/Text/Internal/Search.hs, dist/build/Data/Text/Internal/Search.o ) [27 of 44] Compiling Data.Text.Foreign ( Data/Text/Foreign.hs, dist/build/Data/Text/Foreign.o ) [28 of 44] Compiling Data.Text ( Data/Text.hs, dist/build/Data/Text.o ) Data/Text.hs:558:1: warning: Rule "TEXT compareN/length -> compareLength" may never fire because ‘length’ might inline first Probable fix: add an INLINE[n] or NOINLINE[n] pragma for ‘length’ Data/Text.hs:563:1: warning: Rule "TEXT ==N/length -> compareLength/==EQ" may never fire because ‘length’ might inline first Probable fix: add an INLINE[n] or NOINLINE[n] pragma for ‘length’ Data/Text.hs:568:1: warning: Rule "TEXT /=N/length -> compareLength//=EQ" may never fire because ‘length’ might inline first Probable fix: add an INLINE[n] or NOINLINE[n] pragma for ‘length’ Data/Text.hs:573:1: warning: Rule "TEXT <N/length -> compareLength/==LT" may never fire because ‘length’ might inline first Probable fix: add an INLINE[n] or NOINLINE[n] pragma for ‘length’ Data/Text.hs:578:1: warning: Rule "TEXT <=N/length -> compareLength//=GT" may never fire because ‘length’ might inline first Probable fix: add an INLINE[n] or NOINLINE[n] pragma for ‘length’ Data/Text.hs:583:1: warning: Rule "TEXT >N/length -> compareLength/==GT" may never fire because ‘length’ might inline first Probable fix: add an INLINE[n] or NOINLINE[n] pragma for ‘length’ Data/Text.hs:588:1: warning: Rule "TEXT >=N/length -> compareLength//=LT" may never fire because ‘length’ might inline first Probable fix: add an INLINE[n] or NOINLINE[n] pragma for ‘length’ [29 of 44] Compiling Data.Text.Internal.IO ( Data/Text/Internal/IO.hs, dist/build/Data/Text/Internal/IO.o ) [30 of 44] Compiling Data.Text.IO ( Data/Text/IO.hs, dist/build/Data/Text/IO.o ) [31 of 44] Compiling Data.Text.Internal.Lazy ( Data/Text/Internal/Lazy.hs, dist/build/Data/Text/Internal/Lazy.o ) [32 of 44] Compiling Data.Text.Internal.Lazy.Fusion ( Data/Text/Internal/Lazy/Fusion.hs, dist/build/Data/Text/Internal/Lazy/Fusion.o ) [33 of 44] Compiling Data.Text.Internal.Lazy.Search ( Data/Text/Internal/Lazy/Search.hs, dist/build/Data/Text/Internal/Lazy/Search.o ) [34 of 44] Compiling Data.Text.Lazy.Internal ( Data/Text/Lazy/Internal.hs, dist/build/Data/Text/Lazy/Internal.o ) [35 of 44] Compiling Data.Text.Lazy.Encoding ( Data/Text/Lazy/Encoding.hs, dist/build/Data/Text/Lazy/Encoding.o ) [36 of 44] Compiling Data.Text.Lazy ( Data/Text/Lazy.hs, dist/build/Data/Text/Lazy.o ) Data/Text/Lazy.hs:403:11: warning: Rule "TEXT literal UTF8" may never fire because ‘unpackCStringUtf8#’ might inline first Probable fix: add an INLINE[n] or NOINLINE[n] pragma for ‘unpackCStringUtf8#’ [37 of 44] Compiling Data.Text.Internal.Builder ( Data/Text/Internal/Builder.hs, dist/build/Data/Text/Internal/Builder.o ) Data/Text/Internal/Builder.hs:311:1: warning: Rule "flush/flush" may never fire because ‘flush’ might inline first Probable fix: add an INLINE[n] or NOINLINE[n] pragma for ‘flush’ [38 of 44] Compiling Data.Text.Lazy.Builder ( Data/Text/Lazy/Builder.hs, dist/build/Data/Text/Lazy/Builder.o ) [39 of 44] Compiling Data.Text.Internal.Builder.Functions ( Data/Text/Internal/Builder/Functions.hs, dist/build/Data/Text/Internal/Builder/Functions.o ) [40 of 44] Compiling Data.Text.Lazy.Builder.Int ( Data/Text/Lazy/Builder/Int.hs, dist/build/Data/Text/Lazy/Builder/Int.o ) [41 of 44] Compiling Data.Text.Lazy.IO ( Data/Text/Lazy/IO.hs, dist/build/Data/Text/Lazy/IO.o ) [42 of 44] Compiling Data.Text.Lazy.Read ( Data/Text/Lazy/Read.hs, dist/build/Data/Text/Lazy/Read.o ) Data/Text/Lazy/Read.hs:3:14: warning: ‘Data.Text.Lazy.Read’ is marked as Trustworthy but has been inferred as safe! [43 of 44] Compiling Data.Text.Lazy.Builder.RealFloat ( Data/Text/Lazy/Builder/RealFloat.hs, dist/build/Data/Text/Lazy/Builder/RealFloat.o ) [44 of 44] Compiling Data.Text.Read ( Data/Text/Read.hs, dist/build/Data/Text/Read.o ) In-place registering text-1.2.1.3... Creating package registration file: /tmp/pkgConf-text-1.2.118076.3 Installing library in /home/simonpj/.cabal/lib/x86_64-linux-ghc-7.11.20151125/text_5Rq52TgwV3S3ky6aLF96ly Registering text-1.2.1.3... Installed text-1.2.1.3 Configuring parsec-3.1.9... Building parsec-3.1.9... Preprocessing library parsec-3.1.9... [ 1 of 25] Compiling Text.Parsec.Pos ( Text/Parsec/Pos.hs, dist/build/Text/Parsec/Pos.o ) [ 2 of 25] Compiling Text.Parsec.Error ( Text/Parsec/Error.hs, dist/build/Text/Parsec/Error.o ) [ 3 of 25] Compiling Text.ParserCombinators.Parsec.Error ( Text/ParserCombinators/Parsec/Error.hs, dist/build/Text/ParserCombinators/Parsec/Error.o ) [ 4 of 25] Compiling Text.Parsec.Prim ( Text/Parsec/Prim.hs, dist/build/Text/Parsec/Prim.o ) Text/Parsec/Prim.hs:75:1: error: Bad interface file: /home/simonpj/.cabal/lib/x86_64-linux-ghc-7.11.20151125/text_5Rq52TgwV3S3ky6aLF96ly/Data/Text.hi Something is amiss; requested module text-1.2.1.3@text-1.2.1.3-97fb94aeb32201606fe5187cbce5d852:Data.Text differs from name found in the interface file text_5Rq52TgwV3S3ky6aLF96ly:Data.Text Text/Parsec/Prim.hs:76:1: error: Bad interface file: /home/simonpj/.cabal/lib/x86_64-linux-ghc-7.11.20151125/text_5Rq52TgwV3S3ky6aLF96ly/Data/Text/Lazy.hi Something is amiss; requested module text-1.2.1.3@text-1.2.1.3-97fb94aeb32201606fe5187cbce5d852:Data.Text.Lazy differs from name found in the interface file text_5Rq52TgwV3S3ky6aLF96ly:Data.Text.Lazy Text/Parsec/Prim.hs:80:1: error: Bad interface file: /home/simonpj/.cabal/lib/x86_64-linux-ghc-7.11.20151125/mtl_29yPYQfz4VvKtYIFBb0Wdp/Control/Monad/Trans.hi Something is amiss; requested module mtl-2.2.1@mtl-2.2.1-fd5d2a6f3b4f2b35d982c365df381a09:Control.Monad.Trans differs from name found in the interface file mtl_29yPYQfz4VvKtYIFBb0Wdp:Control.Monad.Trans Text/Parsec/Prim.hs:81:1: error: Bad interface file: /home/simonpj/.cabal/lib/x86_64-linux-ghc-7.11.20151125/mtl_29yPYQfz4VvKtYIFBb0Wdp/Control/Monad/Identity.hi Something is amiss; requested module mtl-2.2.1@mtl-2.2.1-fd5d2a6f3b4f2b35d982c365df381a09:Control.Monad.Identity differs from name found in the interface file mtl_29yPYQfz4VvKtYIFBb0Wdp:Control.Monad.Identity Text/Parsec/Prim.hs:83:1: error: Bad interface file: /home/simonpj/.cabal/lib/x86_64-linux-ghc-7.11.20151125/mtl_29yPYQfz4VvKtYIFBb0Wdp/Control/Monad/Reader/Class.hi Something is amiss; requested module mtl-2.2.1@mtl-2.2.1-fd5d2a6f3b4f2b35d982c365df381a09:Control.Monad.Reader.Class differs from name found in the interface file mtl_29yPYQfz4VvKtYIFBb0Wdp:Control.Monad.Reader.Class Text/Parsec/Prim.hs:84:1: error: Bad interface file: /home/simonpj/.cabal/lib/x86_64-linux-ghc-7.11.20151125/mtl_29yPYQfz4VvKtYIFBb0Wdp/Control/Monad/State/Class.hi Something is amiss; requested module mtl-2.2.1@mtl-2.2.1-fd5d2a6f3b4f2b35d982c365df381a09:Control.Monad.State.Class differs from name found in the interface file mtl_29yPYQfz4VvKtYIFBb0Wdp:Control.Monad.State.Class Text/Parsec/Prim.hs:85:1: error: Bad interface file: /home/simonpj/.cabal/lib/x86_64-linux-ghc-7.11.20151125/mtl_29yPYQfz4VvKtYIFBb0Wdp/Control/Monad/Cont/Class.hi Something is amiss; requested module mtl-2.2.1@mtl-2.2.1-fd5d2a6f3b4f2b35d982c365df381a09:Control.Monad.Cont.Class differs from name found in the interface file mtl_29yPYQfz4VvKtYIFBb0Wdp:Control.Monad.Cont.Class Text/Parsec/Prim.hs:86:1: error: Bad interface file: /home/simonpj/.cabal/lib/x86_64-linux-ghc-7.11.20151125/mtl_29yPYQfz4VvKtYIFBb0Wdp/Control/Monad/Error/Class.hi Something is amiss; requested module mtl-2.2.1@mtl-2.2.1-fd5d2a6f3b4f2b35d982c365df381a09:Control.Monad.Error.Class differs from name found in the interface file mtl_29yPYQfz4VvKtYIFBb0Wdp:Control.Monad.Error.Class Failed to install parsec-3.1.9 cabal: Error: some packages failed to install: parsec-3.1.9 failed during the building phase. The exception was: ExitFailure 1 simonpj@cam-05-unx:~/5builds/HEAD-5$ /home/simonpj/5builds/HEAD-5/inplace/bin/ghc-pkg list /5playpen/simonpj/HEAD-5/inplace/lib/package.conf.d: Cabal-1.23.0.0 array-0.5.1.0 base-4.9.0.0 binary-0.7.5.0 bytestring-0.10.6.0 containers-0.5.6.2 deepseq-1.4.2.0 directory-1.2.5.0 filepath-1.4.1.0 (ghc-7.11.20151125) ghc-boot-0.0.0.0 ghc-prim-0.5.0.0 haskeline-0.7.2.1 hoopl-3.10.2.0 hpc-0.6.0.2 integer-gmp-1.0.0.0 pretty-1.1.2.0 process-1.4.1.0 rts-1.0 template-haskell-2.11.0.0 terminfo-0.4.0.1 time-1.5.0.1 transformers-0.4.3.0 unix-2.7.1.0 xhtml-3000.2.1 /home/simonpj/.ghc/x86_64-linux-7.11.20151125/package.conf.d: mtl-2.2.1 text-1.2.1.3 simonpj@cam-05-unx:~/5builds/HEAD-5$

3 2

ok to do reformatting commits?
by Evan Laforge 02 Dec '15

02 Dec '15

When I was doing a recent patch, I was annoyed by lint errors about >80 lines when I was just conforming to the existing style. To avoid cluttering my commit with unrelated changes, I decided to fix the lints in a formatting-only commit afterwards. Looking in the archives, I see there was some recent discussion about this, but I didn't see anyone volunteering to just go wrap a bunch of files, or saying that they didn't want anyone to do this (usual reason being cluttering the history, which as a rationale to not do formatting only changes never sat too well with me). Would anyone mind if I went and wrapped a bunch of files, say typecheck/*.hs? This seems simpler than either constant hassling from arc or coming up with more elaborate rules for arc. I would have to make some formatting decisions, so likely to some eyes I would be messing some stuff up, but since there's no real standard that is probably unavoidable.

5 6

stranal/sigs/UnsatFun
by Richard Eisenberg 30 Nov '15

30 Nov '15

Hi devs, On my kind=type branch (D808), I have this test failure for stranal/sigs/UnsatFun: ==================== Strictness signatures ==================== UnsatFun.$trModule: m UnsatFun.f: <B,1*U(U)><B,A>b -UnsatFun.g: <B,1*U(U)>b -UnsatFun.g': <L,1*U(U)> +UnsatFun.g: <L,U(U)> +UnsatFun.g': <L,U(U)> UnsatFun.g3: <L,U(U)>m -UnsatFun.h: <C(S),1*C1(U(U))> -UnsatFun.h2: <S,1*U><L,1*C1(U(U))> -UnsatFun.h3: <C(S),1*C1(U)>m +UnsatFun.h: <S,1*U> +UnsatFun.h2: <S,1*U><L,1*U> +UnsatFun.h3: <S,1*U>m *** unexpected failure for UnsatFun(optasm) I haven't any clue what this means. Is it bad? Is it good? Any pointers? Thanks! Richard

3 6

What is causing the "Unrecognized field abi" warning?
by Sven Panne 30 Nov '15

30 Nov '15

This shows up in more recent builds of my packages on Travis CI, e.g. https://travis-ci.org/haskell-opengl/OpenGL/jobs/93814917#L296, but I don't have a clue what's causing it (GHC? cabal? Something else?), if I should ignore it or if I should somehow act on that. :-/ My gut feeling is that it's GHC, but I might be wrong... Cheers, S.

2 2

Remove deprecated quasiquote syntax
by Matthew Pickering 29 Nov '15

29 Nov '15

The [$qq| quasiquote syntax has been deprecated since around 2010. Is there any objection to removing the backwards compatibility now? I counted 216 uses of it on hackage in a handful of packages, some in comments. http://lpaste.net/145938 Here is the commit which deprecated it - https://github.com/ghc/ghc/commit/9ba922ee06b048774d7a82964867ff768a78126e Matt

3 3

Should (~) be homogeneous or heterogeneous?
by Richard Eisenberg 27 Nov '15

27 Nov '15

Hi devs, I'm desperately working toward getting kind equalities in before the feature freeze. It's coming along nicely. But I have a user-facing issue to work out. * Should (~), as written in user code, require the kinds of its arguments to be equal? Another way of asking the same question is: Should the kind of (~) be 1. forall k. k -> k -> Constraint (HEAD) 2. forall k1 k2. k1 -> k2 -> Constraint (my branch, at the moment) Choice #2 is strictly more powerful and cannot be expressed in terms of #1. But #1 is perhaps more intuitive for programmers, who might expect inference to conclude that the two kinds are the same. Here is an example of where the difference matters: > data KProxy k = KP > class kproxy ~ 'KP => C (kproxy :: KProxy k) We can see that the kind of the type variable kproxy should be (KProxy k). But we still have to infer the kind of the occurrence of 'KP on the left. HEAD sees the kind of kproxy and infers that 'KP should have kind (KProxy k). My branch, on the other hand, doesn't have any reason to constrain the kind of 'KP, and so it gets (KProxy Any), which quickly causes trouble. The fix is easy: add a kind signature. I see two ways forward, corresponding to the choices for the kind of (~) above: 1. Make (~) homogeneous and introduce a new constraint (~~) that is like (~) but heterogeneous. We resign ourselves to explaining the technical, subtle difference between (~) and (~~) into perpetuity. 2. Make (~) heterogeneous. Some people will have to add kind annotations to their code to port from GHC 7.10 to GHC 8.0. But these kind annotations will be fully backward-compatible, and won't require CPP, or warnings, or any other bother. We may have to explain why kind inference around (~) is weaker than it was before. I'm (clearly?) leaning toward #2. But I'd like feedback. Thoughts? Thanks! Richard

4 6

Reproducible builds using GHC
by Joachim Breitner 27 Nov '15

27 Nov '15

Hi Bartosz, you might be aware of the reproducible builds project (https://reproducible-builds.org/) which tries to make as much software as possible to build reproducibly, i.e. bitwise identical output files. I have done a few minor things in that direction myself and therefore got invited to the “Reproducibly World Summit” next week in Athens. But by now, you have worked much harder on the problem than I ever have, and so you have a much better overview of the remaining issues. Would you mind posting an update on your work on #4012, about what remains to be done, whether you think that the remaining problems are solved (and just need doing) or whether there are issues without a known solution so far? I know that your focus right now is reproducible interface files, but can you say something about how far away reproducible binary files are, once the interface files are reproducible? Are the causes of non- determinism in principle the same in either case, or are there unique problems when it comes to object files? Are there areas of work where you could need some extra help? Thanks for your input, Joachim -- Joachim “nomeata” Breitner mail(a)joachim-breitner.de • http://www.joachim-breitner.de/ Jabber: nomeata(a)joachim-breitner.de • GPG-Key: 0xF0FBF51F Debian Developer: nomeata(a)debian.org

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