May 2013 - ghc-devs - Haskell.org

Restrictions on polytypes with type families
by Richard Eisenberg 13 Nov '13

13 Nov '13

Hi all, GHC doesn't allow type families to be used with polytypes: 1) The right-hand side of a type family instance cannot have a "forall". 2) A type family cannot be applied to a type containing a "forall". 3) A pattern in a type family instance is (oddly) allowed to contain "forall", but this is silly because of (2). Do these restrictions have known reasons for their existence? Or, are there any that are restricted because someone needs to think hard before lifting it, and no one has yet done that thinking? I know, for example, that the unify function in types/Unify.lhs will have to be completed to work with foralls, but this doesn't seem hard. I've run into two separate cases where I've hit this restriction, so this isn't just idle thought. Thanks, Richard

8 15

HEAD build fails on OS X
by Andreas Voellmy 28 Aug '13

28 Aug '13

I got a fresh copy of HEAD today, and the build failed. The failing command is: $ cd libraries && sh gen_contents_index --intree haddock: internal error: /Users/andreas/repos/temp-ghc-2/ghc-build/inplace/lib/html/Ocean.std-theme/hslogo-16.png: copyFile: does not exist (No such file or directory) I have not yet had time to look into this, but hopefully someone knows what happened here. -Andi

7 17

T3294 variies in whether it fails or not
by Simon Peyton-Jones 14 Jul '13

14 Jul '13

Ian Perf/compiler/T3294 has very different max_bytes_used when BINDIST=YES than without. See below. I don't know why. I don't know whether it matters. Maybe it's just the moment that GC strikes. But it's uncomfortable to have such an erratic test failure. Simon simonpj@cam-05-unx:~/5builds/HEAD-1/testsuite/tests/perf/compiler$ make TEST=T3294 python2 ../../../driver/runtests.py -e ghc_compiler_always_flags="'-fforce-recomp -dcore-lint -dcmm-lint -dno-debug-output -no-user-package-db -rtsopts '" -e ghc_debugged=False -e ghc_with_native_codegen=1 -e ghc_with_vanilla=1 -e ghc_with_dynamic=1 -e ghc_with_profiling=0 -e ghc_with_threaded_rts=1 -e ghc_with_dynamic_rts=1 -e ghc_with_interpreter=1 -e ghc_unregisterised=0 -e ghc_dynamic_by_default=False -e ghc_dynamic=True -e ghc_with_smp=1 -e ghc_with_llvm=1 -e windows=False -e darwin=False -e in_tree_compiler=True -e clean_only=False --rootdir=. --config=../../../config/ghc -e 'config.confdir="../../../config"' -e 'config.compiler="/5playpen/simonpj/HEAD-1/inplace/bin/ghc-stage2"' -e 'config.ghc_pkg="/5playpen/simonpj/HEAD-1/inplace/bin/ghc-pkg"' -e 'config.hp2ps="/5playpen/simonpj/HEAD-1/inplace/bin/hp2ps"' -e 'config.hpc="/5playpen/simonpj/HEAD-1/inplace/bin/hpc"' -e 'config.gs="gs"' -e 'config.platform="x86_64-unknown-linux"' -e 'config.os="linux"' -e 'config.arch="x86_64"' -e 'config.wordsize="64"' -e 'default_testopts.cleanup=""' -e 'config.timeout=int() or config.timeout' -e 'config.timeout_prog="../../../timeout/install-inplace/bin/timeout"' -e 'config.exeext=""' -e 'config.top="/5playpen/simonpj/HEAD-1/testsuite"' \ --only=T3294 \ \ \ \ \ \ Timeout is 300 Found 1 .T files... Beginning test run at Tue May 28 09:21:29 BST 2013 ====> Scanning ./all.T =====> T3294(normal) 2 of 14 [0, 0, 0] cd . && '/5playpen/simonpj/HEAD-1/inplace/bin/ghc-stage2' -fforce-recomp -dno-debug-output -no-user-package-db -rtsopts -fno-ghci-history -c T3294.hs +RTS -V0 -tT3294.comp.stats --machine-readable -RTS >T3294.comp.stderr 2>&1 OVERALL SUMMARY for test run started at Tue May 28 09:21:29 BST 2013 14 total tests, which gave rise to 47 test cases, of which 46 were skipped 0 had missing libraries 1 expected passes 0 expected failures 0 caused framework failures 0 unexpected passes 0 unexpected failures simonpj@cam-05-unx:~/5builds/HEAD-1/testsuite/tests/perf/compiler$ cat T3294.comp.stats /5playpen/simonpj/HEAD-1/inplace/lib/bin/ghc-stage2 -B/5playpen/simonpj/HEAD-1/inplace/lib -fforce-recomp -dno-debug-output -no-user-package-db -rtsopts -fno-ghci-history -c T3294.hs +RTS -V0 -tT3294.comp.stats --machine-readable [("bytes allocated", "2721056936") ,("num_GCs", "540") ,("average_bytes_used", "15190408") ,("max_bytes_used", "36726792") ,("num_byte_usage_samples", "15") ,("peak_megabytes_allocated", "105") ,("init_cpu_seconds", "0.00") ,("init_wall_seconds", "0.00") ,("mutator_cpu_seconds", "2.64") ,("mutator_wall_seconds", "3.25") ,("GC_cpu_seconds", "2.03") ,("GC_wall_seconds", "2.03") ] simonpj@cam-05-unx:~/5builds/HEAD-1/testsuite/tests/perf/compiler$ make TEST=T3294 BINDIST=YES python2 ../../../driver/runtests.py -e ghc_compiler_always_flags="'-fforce-recomp -dcore-lint -dcmm-lint -dno-debug-output -no-user-package-db -rtsopts '" -e ghc_debugged=False -e ghc_with_native_codegen=1 -e ghc_with_vanilla=1 -e ghc_with_dynamic=1 -e ghc_with_profiling=0 -e ghc_with_threaded_rts=1 -e ghc_with_dynamic_rts=1 -e ghc_with_interpreter=1 -e ghc_unregisterised=0 -e ghc_dynamic_by_default=False -e ghc_dynamic=True -e ghc_with_smp=1 -e ghc_with_llvm=1 -e windows=False -e darwin=False -e in_tree_compiler=True -e clean_only=False --rootdir=. --config=../../../config/ghc -e 'config.confdir="../../../config"' -e 'config.compiler="/5playpen/simonpj/HEAD-1/bindisttest/install dir/bin/ghc"' -e 'config.ghc_pkg="/5playpen/simonpj/HEAD-1/bindisttest/install dir/bin/ghc-pkg"' -e 'config.hp2ps="/5playpen/simonpj/HEAD-1/bindisttest/install dir/bin/hp2ps"' -e 'config.hpc="/5playpen/simonpj/HEAD-1/bindisttest/install dir/bin/hpc"' -e 'config.gs="gs"' -e 'config.platform="x86_64-unknown-linux"' -e 'config.os="linux"' -e 'config.arch="x86_64"' -e 'config.wordsize="64"' -e 'default_testopts.cleanup=""' -e 'config.timeout=int() or config.timeout' -e 'config.timeout_prog="../../../timeout/install-inplace/bin/timeout"' -e 'config.exeext=""' -e 'config.top="/5playpen/simonpj/HEAD-1/testsuite"' \ --only=T3294 \ \ \ \ \ \ Timeout is 300 Found 1 .T files... Beginning test run at Tue May 28 09:21:49 BST 2013 ====> Scanning ./all.T =====> T3294(normal) 2 of 14 [0, 0, 0] cd . && '/5playpen/simonpj/HEAD-1/bindisttest/install dir/bin/ghc' -fforce-recomp -dno-debug-output -no-user-package-db -rtsopts -fno-ghci-history -c T3294.hs +RTS -V0 -tT3294.comp.stats --machine-readable -RTS >T3294.comp.stderr 2>&1 max_bytes_used value is too high: Expected max_bytes_used: 36904752 +/-15% Lower bound max_bytes_used: 31369039 Upper bound max_bytes_used: 42440465 Actual max_bytes_used: 43818472 *** unexpected failure for T3294(normal) Unexpected results from: TEST="T3294" OVERALL SUMMARY for test run started at Tue May 28 09:21:49 BST 2013 14 total tests, which gave rise to 47 test cases, of which 46 were skipped 0 had missing libraries 0 expected passes 0 expected failures 0 caused framework failures 0 unexpected passes 1 unexpected failures Unexpected failures: . T3294 [stat not good enough] (normal) simonpj@cam-05-unx:~/5builds/HEAD-1/testsuite/tests/perf/compiler$ cat T3294.comp.stats /5playpen/simonpj/HEAD-1/bindisttest/install dir/lib/ghc-7.7/bin/ghc -B/5playpen/simonpj/HEAD-1/bindisttest/install dir/lib/ghc-7.7 -fforce-recomp -dno-debug-output -no-user-package-db -rtsopts -fno-ghci-history -c T3294.hs +RTS -V0 -tT3294.comp.stats --machine-readable [("bytes allocated", "2724158504") ,("num_GCs", "525") ,("average_bytes_used", "16042228") ,("max_bytes_used", "43818472") ,("num_byte_usage_samples", "15") ,("peak_megabytes_allocated", "116") ,("init_cpu_seconds", "0.00") ,("init_wall_seconds", "0.00") ,("mutator_cpu_seconds", "2.77") ,("mutator_wall_seconds", "3.38") ,("GC_cpu_seconds", "2.38") ,("GC_wall_seconds", "2.38") ] simonpj@cam-05-unx:~/5builds/HEAD-1/testsuite/tests/perf/compiler$

2 1

package installation woes with Template Haskell / dynamic libraries
by Richard Eisenberg 13 Jul '13

13 Jul '13

Hi all, --- tl;dr: cabal fails to install a package where one module in the package uses another module via Template Haskell, requiring a .dyn_o file. The compilation order, though, makes .o files before .dyn_o files, so installation fails. Is this my fault or cabal's? --- I've built and installed HEAD (as of Apr 8), on Mac OS 10.8.2, without specifying a build.mk file (i.e., using the defaults). I then tried to install the singletons package. This package has multiple modules, one of which uses another in some Template Haskell code. The TH code also uses the syb and mtl packages. - A simple `cabal install singletons` fails when compiling the module that uses TH, because there are no .dylib files for the syb or mtl libraries. I add 'shared: True' to my ~/.cabal/config file, "dangerous"ly reinstall mtl and syb and try again. - Now, `cabal install singletons` still fails during compilation, because the TH code looks for Singletons.dyn_o, which doesn't exist. The problem is that the vanilla build happens before the shared build, and TH seems to require the shared build. - I try `cabal install singletons --disable-library-vanilla`, and everything compiles, but then I get this: Installing library in /Users/rae/Library/Haskell/ghc-7.7.20130407/lib/singletons-0.8.5/lib cabal: dist/build/HSsingletons-0.8.5.o: does not exist - In the hopes that cabal kept the .dyn_o files around, I try regular `cabal install singletons`, but cabal seems to have discarded the .dyn_o files and I get the same error as before. - So, I `cabal unpack singletons`, go into the singletons folder, and run `cabal install --disable-library-vanilla`, and get the installation error as before. But, the compile worked and the .dyn_o files are kept! So, a final `cabal install` now works. Phew. I have a relatively weak understanding of cabal. My question is: Is the problem I've run into here based on local settings that need to be fixed? Is there a moving part somewhere that needs to be upgraded? Or, is this a real bug somewhere? If the problem isn't local, I see three separate bugs here: 1) I had to "dangerous"ly reinstall mtl and syb to get the shared libraries after updating my ~/.cabal/config. I think it should be possible to augment an existing package installation with a new "way" without reinstalling. 2) If a package uses TH and depends on another package, and if TH requires dynamic linking, cabal should automatically install dynamic versions of the library, overriding settings in ~/.cabal/config. Or, if overriding settings is a no-no, it should give a stern warning. It would make sense if this dependency were required to be stated in the package's .cabal file. 3) If a package uses TH and depends on itself, similar logic should apply (requiring a dynamic build), and the order of compilation should be fixed. I can understand (but, without more knowledge, would disagree with) an argument discarding 1) and 2) as natural consequences of a silly user, but 3) -- especially the compilation order -- seems more fundamental. I don't know of a way of installing singletons now without unpacking it and dancing around this problem. What do you think? Are these bugs? Am I a silly user? Or both? Thanks! Richard

2 1

Unreliability of the build system
by Jan Stolarek 28 Jun '13

28 Jun '13

Fellow developers, I need advice on using GHC build system. Recently I've been spending more time on resolving problems with the build system itself than on developing GHC, and this is not how things are supposed to be. I have found testsuite and validation to be very unreliable - things seem to break randomly and results are not repeatable. I suspect that I might be doing something wrong and I will appreciate any advice or explanations why I'm having these problem. I have three GHC trees: * ghc-working - source tree I use for development * ghc-build - lndir'ed to ghc-working, used for building * ghc-validate - source tree used for validation, ghc-working is set up as one of the remotes Here's the situation from yesterday evening. I updated ghc-working and ghc-validate trees from the origin - according to the fingerprint.py script both trees were identical. I ran validation in ghc-validate and ghc-build trees (on the master branches, no my changes). The only difference between them should be that ghc-build is symlinked. Validation in ghc-validate passed with two failures (others on IRC confirmed they are having same failures), while validation in ghc-build failed with: Haddock coverage: 100% ( 1 / 1) in 'GHC.IntWord64' 78% ( 7 / 9) in 'GHC.Types' 17% ( 1 / 6) in 'GHC.CString' 3% ( 2 / 63) in 'GHC.Tuple' 0% ( 0 / 3) in 'GHC.Debug' 0% ( 0 /342) in 'GHC.PrimopWrappers' 30% (160 /531) in 'GHC.Prim' 100% ( 3 / 3) in 'GHC.Magic' 38% ( 6 / 16) in 'GHC.Classes' haddock: internal error: /dane/uczelnia/projekty/ghc-build/inpl ace/lib/html/Ocean.std-theme/ocean.css: copyFile: does not exis t (No such file or directory) gmake[1]: *** [libraries/ghc-prim/dist-install/doc/html/ghc-pri m/ghc-prim.haddock] Błąd 1 gmake[1]: *** Kasuję plik `libraries/ghc-prim/dist-install/doc/ html/ghc-prim/ghc-prim.haddock' Today I ran ./sync-all pull in both trees, but no new commits were added (according to fingerprint). I run the validation again and the validation in ghc-build fails as previously, while the validation in ghc-validate reports over 200 unexpected failures. What is more, I found that rerunning some of the failing tests (make TEST=whatever) often results with these tests passing. This unreliability is very frustrating. I've been having these problems since I started working on GHC in December. I'm wondering whether this is a common thing or am I doing something not-so-obviously wrong? As usual, I will appreciate any advice from those more experienced than me. Janek

8 39

Stage1Only
by Trevor Elliott 28 Jun '13

28 Jun '13

Hi Everyone, I've been trying to produce just a stage1 compiler by setting Stage1Only in my mk/build.mk. What I've been discovering, is that the build system seems to ignore this (or I haven't set it in the right place) and trys to build a stage2 compiler and its associated tools. What is the best way to stop the build system after stage1 + libraries has finished? Thanks! --trevor

4 14

Integer constant folding in the presence of new primops
by Jan Stolarek 20 Jun '13

20 Jun '13

I'm finishing my patches for T6135, but I still have some work to do on integer-gmp and integer-simpl libraries. I changed the previously existing functions that compare Integers: {-# NOINLINE #-} eqInteger :: Integer -> Integer -> Bool eqInteger = ... to something like this: {-# NOINLINE eqIntegerPrim #-} eqIntegerPrim :: Integer -> Integer -> Int# eqIntegerPrim ... -- same as before, but uses new primops eqInteger :: Integer -> Integer -> Bool eqInteger a b = tagToEnum# (a `eqIntegerPrim` b) I noticed that in some cases this implementation prevents constant folding for Integers. I'm trying to figure out the proper way to fix this. I am considering two ways of doing it: - add new folding rules for eqIntegerPrim and other functions, leave the existing rules for eqInteger. This should fold: (100012 :: Integer) == 100012 to True (as it does now) - add new folding rules for eqIntegerPrim and other functions, remove the existing rules for eqInteger. This would fold (100012 :: Integer) == 100012 to tagToEnum# 1# Which approach is better? Another question related to this: how do I run validation with integer-simpl enabled? Wiki describes how to enable integer-simpl for the build, but I think that validation is always run against integer-gmp? Or am I wrong here? Janek

5 11

Validate fails: Var/Type length mismatch: [] [s{tv a15I} [tv]]
by Ian Lynagh 06 Jun '13

06 Jun '13

Hi all, The validate build is failing for me with the below. Does anyone know what's up please? Thanks Ian ===--- building phase 0 make -r --no-print-directory -f ghc.mk phase=0 phase_0_builds make[1]: Nothing to be done for `phase_0_builds'. ===--- building phase 1 make -r --no-print-directory -f ghc.mk phase=1 phase_1_builds ===--- building final phase make -r --no-print-directory -f ghc.mk phase=final all "inplace/bin/ghc-stage2" -hisuf hi -osuf o -hcsuf hc -static -H32m -O -Werror -Wall -H64m -O0 -package-name dph-prim-par-0.8.0.1 -hide-all-packages -i -ilibraries/dph/dph-prim-par/. -ilibraries/dph/dph-prim-par/dist-install/build -ilibraries/dph/dph-prim-par/dist-install/build/autogen -Ilibraries/dph/dph-prim-par/dist-install/build -Ilibraries/dph/dph-prim-par/dist-install/build/autogen -Ilibraries/dph/dph-prim-par/. -optP-include -optPlibraries/dph/dph-prim-par/dist-install/build/autogen/cabal_macros.h -package base-4.7.0.0 -package dph-base-0.8.0.1 -package dph-prim-interface-0.8.0.1 -package dph-prim-seq-0.8.0.1 -package old-time-1.1.0.1 -package random-1.0.1.1 -package vector-0.9.1 -Odph -funbox-strict-fields -fcpr-off -Wall -XHaskell98 -XTypeFamilies -XGADTs -XRankNTypes -XBangPatterns -XMagicHash -XUnboxedTuples -XTypeOperators -XFlexibleInstances -XFlexibleContexts -O2 -O -dcore-lint -fno-warn-deprecated-flags -no-user-package-db -rtsopts -Wwarn -odir libraries/dph/dph-prim-par/dist-install/build -hidir libraries/dph/dph-prim-par/dist-install/build -stubdir libraries/dph/dph-prim-par/dist-install/build -dynamic-too -c libraries/dph/dph-prim-par/./Data/Array/Parallel/Unlifted/Distributed/Data/USegd/DT.hs -o libraries/dph/dph-prim-par/dist-install/build/Data/Array/Parallel/Unlifted/Distributed/Data/USegd/DT.o -dyno libraries/dph/dph-prim-par/dist-install/build/Data/Array/Parallel/Unlifted/Distributed/Data/USegd/DT.dyn_o Var/Type length mismatch: [] [s{tv a15I} [tv]] ghc-stage2: panic! (the 'impossible' happened) (GHC version 7.7.20130530 for x86_64-unknown-linux): Iface Lint failure In interface for dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Data.Vector Unfolding of dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Data.Vector.$fDTVector_$cnewMD{v rS} <no location info>: Warning: In the expression: base:Control.Monad.liftM2{v rC} [gid] @ (dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Primitive.DT.MDist{tc rD} ghc-prim:GHC.Types.Int{(w) tc 3J} s3{tv a1Zk} [tv]) @ (vector-0.9.1:Data.Vector.Mutable.STVector{tc rB} s3{tv a1Zk} [tv] (vector-0.9.1:Data.Vector.Unboxed.Base.Vector{tc rU} a4{tv a1Zi} [tv])) @ (dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Primitive.DT.MDist{tc rD} (vector-0.9.1:Data.Vector.Unboxed.Base.Vector{tc rU} a4{tv a1Zi} [tv]) s3{tv a1Zk} [tv]) @ (base:GHC.ST.ST{tc rE} s3{tv a1Zk} [tv]) (base:GHC.ST.$fMonadST{v rA} [gid[DFunId]] @ s3{tv a1Zk} [tv]) (dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Data.Vector.$WMDVector{v rz} [gid[DataConWrapper]] @ a4{tv a1Zi} [tv] @ s3{tv a1Zk} [tv]) ((dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Data.Scalar.Base.$fDTInt8{v ry} [gid] @ s3{tv a1Zk} [tv] g{v a1Zl} [lid]) `cast` (Sym (base:GHC.ST.NTCo:ST{tc rx}[0] <s3{tv a1Zk} [tv]> <dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Primitive.DT.MDist{tc rD} ghc-prim:GHC.Types.Int{(w) tc 3J} s3{tv a1Zk} [tv]>) :: base:GHC.ST.STRep{tc r1j3} s3{tv a1Zk} [tv] (dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Primitive.DT.MDist{tc rD} ghc-prim:GHC.Types.Int{(w) tc 3J} s3{tv a1Zk} [tv]) ~# base:GHC.ST.ST{tc rE} s3{tv a1Zk} [tv] (dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Primitive.DT.MDist{tc rD} ghc-prim:GHC.Types.Int{(w) tc 3J} s3{tv a1Zk} [tv]))) ((\ (s4{v a21s} [lid] :: ghc-prim:GHC.Prim.State#{(w) tc 32q} s3{tv a1Zk} [tv]) -> case vector-0.9.1:Data.Vector.Fusion.Util.delay_inline{v rw} [gid] @ ghc-prim:GHC.Types.Int{(w) tc 3J} @ (ghc-prim:GHC.Types.Int{(w) tc 3J} -> ghc-prim:GHC.Types.Int{(w) tc 3J}) ghc-prim:GHC.Classes.$fOrdInt_$cmax{v rv} [gid] (ghc-prim:GHC.Types.I#{(w) v 6d} [gid[DataCon]] 0) (case g{v a1Zl} [lid] {ghc-prim:GHC.Types.Int{(w) tc 3J}} of (wild{v a27g} [lid] :: dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Primitive.Gang.Gang{tc rF}) { dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Primitive.Gang.Gang{d ru} (dt{v a27R} [lid] :: ghc-prim:GHC.Prim.Int#{(w) tc 3G}) (ds1{v a27S} [lid] :: [base:GHC.MVar.MVar{tc r1Q2} dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Primitive.Gang.Req{tc r1Q1}]) (ds2{v a27T} [lid] :: base:GHC.MVar.MVar{tc r1Q2} ghc-prim:GHC.Types.Bool{(w) tc 3c}) -> ghc-prim:GHC.Types.I#{(w) v 6d} [gid[DataCon]] dt{v a27R} [lid] }) {(# ghc-prim:GHC.Prim.State#{(w) tc 32q} s3{tv a1Zk} [tv], vector-0.9.1:Data.Vector.Mutable.MVector{tc rq} (primitive-0.4.0.1:Control.Monad.Primitive.PrimState{tc rt} (base:GHC.ST.ST{tc rE} s3{tv a1Zk} [tv])) (vector-0.9.1:Data.Vector.Unboxed.Base.Vector{tc rU} a4{tv a1Zi} [tv]) #)} of (wild{v a27V} [lid] :: ghc-prim:GHC.Types.Int{(w) tc 3J}) { ghc-prim:GHC.Types.I#{(w) d 6c} (n#{v a280} [lid] :: ghc-prim:GHC.Prim.Int#{(w) tc 3G}) -> case ghc-prim:GHC.Prim.newArray#{(w) v 920} [gid[PrimOp]] @ (vector-0.9.1:Data.Vector.Unboxed.Base.Vector{tc rU} a4{tv a1Zi} [tv]) @ (primitive-0.4.0.1:Control.Monad.Primitive.PrimState{tc rt} (base:GHC.ST.ST{tc rE} s3{tv a1Zk} [tv])) n#{v a280} [lid] (base:GHC.Err.error{(w) v 05} [gid] @ (vector-0.9.1:Data.Vector.Unboxed.Base.Vector{tc rU} a4{tv a1Zi} [tv]) (ghc-prim:GHC.CString.unpackCString#{v 0k} [gid] "MDist (Vector a) - uninitalised"#)) (s4{v a21s} [lid] `cast` (ghc-prim:GHC.Prim.State#{(w) tc 32q} (Sym (primitive-0.4.0.1:Control.Monad.Primitive.TFCo:R:PrimStateST{tc rs}[0] <s3{tv a1Zk} [tv]>)) :: ghc-prim:GHC.Prim.State#{(w) tc 32q} s3{tv a1Zk} [tv] ~# ghc-prim:GHC.Prim.State#{(w) tc 32q} (primitive-0.4.0.1:Control.Monad.Primitive.PrimState{tc rt} (base:GHC.ST.ST{tc rE} s3{tv a1Zk} [tv])))) {(# ghc-prim:GHC.Prim.State#{(w) tc 32q} s3{tv a1Zk} [tv], vector-0.9.1:Data.Vector.Mutable.MVector{tc rq} (primitive-0.4.0.1:Control.Monad.Primitive.PrimState{tc rt} (base:GHC.ST.ST{tc rE} s3{tv a1Zk} [tv])) (vector-0.9.1:Data.Vector.Unboxed.Base.Vector{tc rU} a4{tv a1Zi} [tv]) #)} of (ds1{v a282} [lid] :: (# ghc-prim:GHC.Prim.State#{(w) tc 32q} (primitive-0.4.0.1:Control.Monad.Primitive.PrimState{tc rt} (base:GHC.ST.ST{tc rE} s3{tv a1Zk} [tv])), ghc-prim:GHC.Prim.MutableArray#{(w) tc 31m} (primitive-0.4.0.1:Control.Monad.Primitive.PrimState{tc rt} (base:GHC.ST.ST{tc rE} s3{tv a1Zk} [tv])) (vector-0.9.1:Data.Vector.Unboxed.Base.Vector{tc rU} a4{tv a1Zi} [tv]) #)) { (# (ipv{v a284} [lid] :: ghc-prim:GHC.Prim.State#{(w) tc 32q} (primitive-0.4.0.1:Control.Monad.Primitive.PrimState{tc rt} (base:GHC.ST.ST{tc rE} s3{tv a1Zk} [tv]))), (ipv1{v a285} [lid] :: ghc-prim:GHC.Prim.MutableArray#{(w) tc 31m} (primitive-0.4.0.1:Control.Monad.Primitive.PrimState{tc rt} (base:GHC.ST.ST{tc rE} s3{tv a1Zk} [tv])) (vector-0.9.1:Data.Vector.Unboxed.Base.Vector{tc rU} a4{tv a1Zi} [tv])) #) -> (# ipv{v a284} [lid] `cast` (ghc-prim:GHC.Prim.State#{(w) tc 32q} (primitive-0.4.0.1:Control.Monad.Primitive.TFCo:R:PrimStateST{tc rs}[0] <s3{tv a1Zk} [tv]>) :: ghc-prim:GHC.Prim.State#{(w) tc 32q} (primitive-0.4.0.1:Control.Monad.Primitive.PrimState{tc rt} (base:GHC.ST.ST{tc rE} s3{tv a1Zk} [tv])) ~# ghc-prim:GHC.Prim.State#{(w) tc 32q} s3{tv a1Zk} [tv]), vector-0.9.1:Data.Vector.Mutable.MVector{v rr} [gid[DataCon]] @ (primitive-0.4.0.1:Control.Monad.Primitive.PrimState{tc rt} (base:GHC.ST.ST{tc rE} s3{tv a1Zk} [tv])) @ (vector-0.9.1:Data.Vector.Unboxed.Base.Vector{tc rU} a4{tv a1Zi} [tv]) 0 n#{v a280} [lid] ipv1{v a285} [lid] #) } }) `cast` (Sym (base:GHC.ST.NTCo:ST{tc rx}[0] <s3{tv a1Zk} [tv]> (vector-0.9.1:Data.Vector.Mutable.MVector{tc rq} (Sym (primitive-0.4.0.1:Control.Monad.Primitive.TFCo:R:PrimStateST{tc rs}[0] <s3{tv a1Zk} [tv]>)) <vector-0.9.1:Data.Vector.Unboxed.Base.Vector{tc rU} a4{tv a1Zi} [tv]>)) :: base:GHC.ST.STRep{tc r1j3} s3{tv a1Zk} [tv] (vector-0.9.1:Data.Vector.Mutable.MVector{tc rq} (primitive-0.4.0.1:Control.Monad.Primitive.PrimState{tc rt} (base:GHC.ST.ST{tc rE} s3{tv a1Zk} [tv])) (vector-0.9.1:Data.Vector.Unboxed.Base.Vector{tc rU} a4{tv a1Zi} [tv])) ~# base:GHC.ST.ST{tc rE} s3{tv a1Zk} [tv] (vector-0.9.1:Data.Vector.Mutable.MVector{tc rq} s3{tv a1Zk} [tv] (vector-0.9.1:Data.Vector.Unboxed.Base.Vector{tc rU} a4{tv a1Zi} [tv])))) Argument value doesn't match argument type: Fun type: (dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Primitive.DT.MDist{tc rD} ghc-prim:GHC.Types.Int{(w) tc 3J} s3{tv a1Zk} [tv] -> vector-0.9.1:Data.Vector.Mutable.STVector{tc rB} s3{tv a1Zk} [tv] (vector-0.9.1:Data.Vector.Unboxed.Base.Vector{tc rU} a4{tv a1Zi} [tv]) -> dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Primitive.DT.MDist{tc rD} (vector-0.9.1:Data.Vector.Unboxed.Base.Vector{tc rU} a4{tv a1Zi} [tv]) s3{tv a1Zk} [tv]) -> base:GHC.ST.ST{tc rE} s3{tv a1Zk} [tv] (dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Primitive.DT.MDist{tc rD} ghc-prim:GHC.Types.Int{(w) tc 3J} s3{tv a1Zk} [tv]) -> base:GHC.ST.ST{tc rE} s3{tv a1Zk} [tv] (vector-0.9.1:Data.Vector.Mutable.STVector{tc rB} s3{tv a1Zk} [tv] (vector-0.9.1:Data.Vector.Unboxed.Base.Vector{tc rU} a4{tv a1Zi} [tv])) -> base:GHC.ST.ST{tc rE} s3{tv a1Zk} [tv] (dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Primitive.DT.MDist{tc rD} (vector-0.9.1:Data.Vector.Unboxed.Base.Vector{tc rU} a4{tv a1Zi} [tv]) s3{tv a1Zk} [tv]) Arg type: dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Primitive.DT.MDist{tc rD} ghc-prim:GHC.Types.Int{(w) tc 3J} s3{tv a1Zk} [tv] -> vector-0.9.1:Data.Vector.Mutable.STVector{tc rB} s3{tv a1Zk} [tv] (vector-0.9.1:Data.Vector.Unboxed.Base.Vector{tc rU} a4{tv a1Zi} [tv]) -> dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Primitive.DT.MDist{tc rD} (vector-0.9.1:Data.Vector.Unboxed.Base.Vector{tc rU} a4{tv a1Zi} [tv]) Arg: dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Data.Vector.$WMDVector{v rz} [gid[DataConWrapper]] @ a4{tv a1Zi} [tv] @ s3{tv a1Zk} [tv] dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Data.Vector.$fDTVector_$cnewMD{v rS} = \ (@ a4{tv a1Zi} [tv]) ($dUnbox{v a1Zj} [lid] :: vector-0.9.1:Data.Vector.Unboxed.Base.Unbox{tc rW} a4{tv a1Zi} [tv]) (@ s3{tv a1Zk} [tv]) (g{v a1Zl} [lid] :: dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Primitive.Gang.Gang{tc rF}) -> base:Control.Monad.liftM2{v rC} [gid] @ (dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Primitive.DT.MDist{tc rD} ghc-prim:GHC.Types.Int{(w) tc 3J} s3{tv a1Zk} [tv]) @ (vector-0.9.1:Data.Vector.Mutable.STVector{tc rB} s3{tv a1Zk} [tv] (vector-0.9.1:Data.Vector.Unboxed.Base.Vector{tc rU} a4{tv a1Zi} [tv])) @ (dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Primitive.DT.MDist{tc rD} (vector-0.9.1:Data.Vector.Unboxed.Base.Vector{tc rU} a4{tv a1Zi} [tv]) s3{tv a1Zk} [tv]) @ (base:GHC.ST.ST{tc rE} s3{tv a1Zk} [tv]) (base:GHC.ST.$fMonadST{v rA} [gid[DFunId]] @ s3{tv a1Zk} [tv]) (dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Data.Vector.$WMDVector{v rz} [gid[DataConWrapper]] @ a4{tv a1Zi} [tv] @ s3{tv a1Zk} [tv]) ((dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Data.Scalar.Base.$fDTInt8{v ry} [gid] @ s3{tv a1Zk} [tv] g{v a1Zl} [lid]) `cast` (Sym (base:GHC.ST.NTCo:ST{tc rx}[0] <s3{tv a1Zk} [tv]> <dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Primitive.DT.MDist{tc rD} ghc-prim:GHC.Types.Int{(w) tc 3J} s3{tv a1Zk} [tv]>) :: base:GHC.ST.STRep{tc r1j3} s3{tv a1Zk} [tv] (dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Primitive.DT.MDist{tc rD} ghc-prim:GHC.Types.Int{(w) tc 3J} s3{tv a1Zk} [tv]) ~# base:GHC.ST.ST{tc rE} s3{tv a1Zk} [tv] (dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Primitive.DT.MDist{tc rD} ghc-prim:GHC.Types.Int{(w) tc 3J} s3{tv a1Zk} [tv]))) ((\ (s4{v a21s} [lid] :: ghc-prim:GHC.Prim.State#{(w) tc 32q} s3{tv a1Zk} [tv]) -> case vector-0.9.1:Data.Vector.Fusion.Util.delay_inline{v rw} [gid] @ ghc-prim:GHC.Types.Int{(w) tc 3J} @ (ghc-prim:GHC.Types.Int{(w) tc 3J} -> ghc-prim:GHC.Types.Int{(w) tc 3J}) ghc-prim:GHC.Classes.$fOrdInt_$cmax{v rv} [gid] (ghc-prim:GHC.Types.I#{(w) v 6d} [gid[DataCon]] 0) (case g{v a1Zl} [lid] {ghc-prim:GHC.Types.Int{(w) tc 3J}} of (wild{v a27g} [lid] :: dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Primitive.Gang.Gang{tc rF}) { dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Primitive.Gang.Gang{d ru} (dt{v a27R} [lid] :: ghc-prim:GHC.Prim.Int#{(w) tc 3G}) (ds1{v a27S} [lid] :: [base:GHC.MVar.MVar{tc r1Q2} dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Primitive.Gang.Req{tc r1Q1}]) (ds2{v a27T} [lid] :: base:GHC.MVar.MVar{tc r1Q2} ghc-prim:GHC.Types.Bool{(w) tc 3c}) -> ghc-prim:GHC.Types.I#{(w) v 6d} [gid[DataCon]] dt{v a27R} [lid] }) {(# ghc-prim:GHC.Prim.State#{(w) tc 32q} s3{tv a1Zk} [tv], vector-0.9.1:Data.Vector.Mutable.MVector{tc rq} (primitive-0.4.0.1:Control.Monad.Primitive.PrimState{tc rt} (base:GHC.ST.ST{tc rE} s3{tv a1Zk} [tv])) (vector-0.9.1:Data.Vector.Unboxed.Base.Vector{tc rU} a4{tv a1Zi} [tv]) #)} of (wild{v a27V} [lid] :: ghc-prim:GHC.Types.Int{(w) tc 3J}) { ghc-prim:GHC.Types.I#{(w) d 6c} (n#{v a280} [lid] :: ghc-prim:GHC.Prim.Int#{(w) tc 3G}) -> case ghc-prim:GHC.Prim.newArray#{(w) v 920} [gid[PrimOp]] @ (vector-0.9.1:Data.Vector.Unboxed.Base.Vector{tc rU} a4{tv a1Zi} [tv]) @ (primitive-0.4.0.1:Control.Monad.Primitive.PrimState{tc rt} (base:GHC.ST.ST{tc rE} s3{tv a1Zk} [tv])) n#{v a280} [lid] (base:GHC.Err.error{(w) v 05} [gid] @ (vector-0.9.1:Data.Vector.Unboxed.Base.Vector{tc rU} a4{tv a1Zi} [tv]) (ghc-prim:GHC.CString.unpackCString#{v 0k} [gid] "MDist (Vector a) - uninitalised"#)) (s4{v a21s} [lid] `cast` (ghc-prim:GHC.Prim.State#{(w) tc 32q} (Sym (primitive-0.4.0.1:Control.Monad.Primitive.TFCo:R:PrimStateST{tc rs}[0] <s3{tv a1Zk} [tv]>)) :: ghc-prim:GHC.Prim.State#{(w) tc 32q} s3{tv a1Zk} [tv] ~# ghc-prim:GHC.Prim.State#{(w) tc 32q} (primitive-0.4.0.1:Control.Monad.Primitive.PrimState{tc rt} (base:GHC.ST.ST{tc rE} s3{tv a1Zk} [tv])))) {(# ghc-prim:GHC.Prim.State#{(w) tc 32q} s3{tv a1Zk} [tv], vector-0.9.1:Data.Vector.Mutable.MVector{tc rq} (primitive-0.4.0.1:Control.Monad.Primitive.PrimState{tc rt} (base:GHC.ST.ST{tc rE} s3{tv a1Zk} [tv])) (vector-0.9.1:Data.Vector.Unboxed.Base.Vector{tc rU} a4{tv a1Zi} [tv]) #)} of (ds1{v a282} [lid] :: (# ghc-prim:GHC.Prim.State#{(w) tc 32q} (primitive-0.4.0.1:Control.Monad.Primitive.PrimState{tc rt} (base:GHC.ST.ST{tc rE} s3{tv a1Zk} [tv])), ghc-prim:GHC.Prim.MutableArray#{(w) tc 31m} (primitive-0.4.0.1:Control.Monad.Primitive.PrimState{tc rt} (base:GHC.ST.ST{tc rE} s3{tv a1Zk} [tv])) (vector-0.9.1:Data.Vector.Unboxed.Base.Vector{tc rU} a4{tv a1Zi} [tv]) #)) { (# (ipv{v a284} [lid] :: ghc-prim:GHC.Prim.State#{(w) tc 32q} (primitive-0.4.0.1:Control.Monad.Primitive.PrimState{tc rt} (base:GHC.ST.ST{tc rE} s3{tv a1Zk} [tv]))), (ipv1{v a285} [lid] :: ghc-prim:GHC.Prim.MutableArray#{(w) tc 31m} (primitive-0.4.0.1:Control.Monad.Primitive.PrimState{tc rt} (base:GHC.ST.ST{tc rE} s3{tv a1Zk} [tv])) (vector-0.9.1:Data.Vector.Unboxed.Base.Vector{tc rU} a4{tv a1Zi} [tv])) #) -> (# ipv{v a284} [lid] `cast` (ghc-prim:GHC.Prim.State#{(w) tc 32q} (primitive-0.4.0.1:Control.Monad.Primitive.TFCo:R:PrimStateST{tc rs}[0] <s3{tv a1Zk} [tv]>) :: ghc-prim:GHC.Prim.State#{(w) tc 32q} (primitive-0.4.0.1:Control.Monad.Primitive.PrimState{tc rt} (base:GHC.ST.ST{tc rE} s3{tv a1Zk} [tv])) ~# ghc-prim:GHC.Prim.State#{(w) tc 32q} s3{tv a1Zk} [tv]), vector-0.9.1:Data.Vector.Mutable.MVector{v rr} [gid[DataCon]] @ (primitive-0.4.0.1:Control.Monad.Primitive.PrimState{tc rt} (base:GHC.ST.ST{tc rE} s3{tv a1Zk} [tv])) @ (vector-0.9.1:Data.Vector.Unboxed.Base.Vector{tc rU} a4{tv a1Zi} [tv]) 0 n#{v a280} [lid] ipv1{v a285} [lid] #) } }) `cast` (Sym (base:GHC.ST.NTCo:ST{tc rx}[0] <s3{tv a1Zk} [tv]> (vector-0.9.1:Data.Vector.Mutable.MVector{tc rq} (Sym (primitive-0.4.0.1:Control.Monad.Primitive.TFCo:R:PrimStateST{tc rs}[0] <s3{tv a1Zk} [tv]>)) <vector-0.9.1:Data.Vector.Unboxed.Base.Vector{tc rU} a4{tv a1Zi} [tv]>)) :: base:GHC.ST.STRep{tc r1j3} s3{tv a1Zk} [tv] (vector-0.9.1:Data.Vector.Mutable.MVector{tc rq} (primitive-0.4.0.1:Control.Monad.Primitive.PrimState{tc rt} (base:GHC.ST.ST{tc rE} s3{tv a1Zk} [tv])) (vector-0.9.1:Data.Vector.Unboxed.Base.Vector{tc rU} a4{tv a1Zi} [tv])) ~# base:GHC.ST.ST{tc rE} s3{tv a1Zk} [tv] (vector-0.9.1:Data.Vector.Mutable.MVector{tc rq} s3{tv a1Zk} [tv] (vector-0.9.1:Data.Vector.Unboxed.Base.Vector{tc rU} a4{tv a1Zi} [tv])))) Iface expr = \ @ a4 $dUnbox :: vector-0.9.1:Data.Vector.Unboxed.Base.Unbox{tc rW} a4 @ s3 g :: dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Primitive.Gang.Gang{tc rF} -> base:Control.Monad.liftM2{v rC} @ (dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Primitive.DT.MDist{tc rD} ghc-prim:GHC.Types.Int{(w) tc 3J} s3) @ (vector-0.9.1:Data.Vector.Mutable.STVector{tc rB} s3 (vector-0.9.1:Data.Vector.Unboxed.Base.Vector{tc rU} a4)) @ (dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Primitive.DT.MDist{tc rD} (vector-0.9.1:Data.Vector.Unboxed.Base.Vector{tc rU} a4) s3) @ (base:GHC.ST.ST{tc rE} s3) (base:GHC.ST.$fMonadST{v rA} @ s3) (dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Data.Vector.$WMDVector{v rz} @ a4 @ s3) (dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Data.Scalar.Base.$fDTInt8{v ry} @ s3 g) `cast` (Sym (base:GHC.ST.NTCo:ST{tc rx}[0] (Refl s3) (Refl (dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Primitive.DT.MDist{tc rD} ghc-prim:GHC.Types.Int{(w) tc 3J} s3)))) (\ s4 :: ghc-prim:GHC.Prim.State#{(w) tc 32q} s3 -> case vector-0.9.1:Data.Vector.Fusion.Util.delay_inline{v rw} @ ghc-prim:GHC.Types.Int{(w) tc 3J} @ (ghc-prim:GHC.Types.Int{(w) tc 3J} -> ghc-prim:GHC.Types.Int{(w) tc 3J}) ghc-prim:GHC.Classes.$fOrdInt_$cmax{v rv} (ghc-prim:GHC.Types.I#{(w) v 6d} 0) (case g of wild { dph-prim-par-0.8.0.1:Data.Array.Parallel.Unlifted.Distributed.Primitive.Gang.Gang{d ru} dt ds1 ds2 -> ghc-prim:GHC.Types.I#{(w) v 6d} dt }) of wild { ghc-prim:GHC.Types.I#{(w) d 6c} n# -> case ghc-prim:GHC.Prim.newArray#{(w) v 920} @ (vector-0.9.1:Data.Vector.Unboxed.Base.Vector{tc rU} a4) @ (primitive-0.4.0.1:Control.Monad.Primitive.PrimState{tc rt} (base:GHC.ST.ST{tc rE} s3)) n# (base:GHC.Err.error{(w) v 05} @ (vector-0.9.1:Data.Vector.Unboxed.Base.Vector{tc rU} a4) (ghc-prim:GHC.CString.unpackCString#{v 0k} "MDist (Vector a) - uninitalised"#)) s4 `cast` (ghc-prim:GHC.Prim.State#{(w) tc 32q} (Sym (primitive-0.4.0.1:Control.Monad.Primitive.TFCo:R:PrimStateST{tc rs}[0] (Refl s3)))) of ds1 { ghc-prim:GHC.Prim.(#,#){(w) d 84} ipv ipv1 -> (# ipv `cast` (ghc-prim:GHC.Prim.State#{(w) tc 32q} (primitive-0.4.0.1:Control.Monad.Primitive.TFCo:R:PrimStateST{tc rs}[0] (Refl s3))), vector-0.9.1:Data.Vector.Mutable.MVector{v rr} @ (primitive-0.4.0.1:Control.Monad.Primitive.PrimState{tc rt} (base:GHC.ST.ST{tc rE} s3)) @ (vector-0.9.1:Data.Vector.Unboxed.Base.Vector{tc rU} a4) 0 n# ipv1 #) } }) `cast` (Sym (base:GHC.ST.NTCo:ST{tc rx}[0] (Refl s3) (vector-0.9.1:Data.Vector.Mutable.MVector{tc rq} (Sym (primitive-0.4.0.1:Control.Monad.Primitive.TFCo:R:PrimStateST{tc rs}[0] (Refl s3))) (Refl (vector-0.9.1:Data.Vector.Unboxed.Base.Vector{tc rU} a4))))) Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug make[1]: *** [libraries/dph/dph-prim-par/dist-install/build/Data/Array/Parallel/Unlifted/Distributed/Data/USegd/DT.o] Error 1 make: *** [all] Error 2

5 15

Test failure
by Simon Peyton-Jones 01 Jun '13

01 Jun '13

Austin Your new test, CatPairs, has an odd commit message: commit e0481fc664c16ba3c118506e153d8b27c3c2c9c8 Author: Austin Seipp <aseipp(a)pobox.com> Date: Thu May 30 08:28:11 2013 -0500 Whoops. :( Moreover, It fails, thus: CatPairs.hs:28:31: The first argument of ‛Category’ should have kind ‛* -> * -> *’, but ‛WrapPipe m’ has kind ‛(,) * * -> (,) * * -> *’ In the instance declaration for ‛Category (WrapPipe m)’ I'm not sure what is supposed to happen. Could you fix please? Thanks Simon

2 3

atMost in GHC.Event.PSQ causes seqfault or bus error
by Kazu Yamamoto 31 May '13

31 May '13

Hi, threadDelay of GHC head causes seqfault or bus error on 32bit machine including Mac and Linux. This bug does not exist as least in GHC 7.4.2. This bug is due to atMost of GHC.Event.PSQ. After modifying libraries/base/base.cabal to export GHC.Event and building GHC head, the following code (compiled by the GHC head with -threaded) causes segfault or bus error: main :: IO () main = do s <- newSource ents <- replicateM 100 (entry s) let q = fold ents print $ Q.atMost 1.5 q fold :: [(Q.Key, Q.Prio)] -> Q.PSQ () fold [] = Q.empty fold ((u,r):xs) = Q.insert u r () $ fold xs entry :: UniqueSource -> IO (Q.Key, Q.Prio) entry s = do u <- newUnique s r <- randomIO return (u,r) But if I copy GHC.Event.PSQ and GHC.Event.Unique, modify their module names, and compile the above code with them, no segfault/bus error happens. I have been tracking this for a long time but I have no idea why this happens. Any advice would be highly appreciated. For more information, please refer to: http://hackage.haskell.org/trac/ghc/ticket/7715 --Kazu

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