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Deriving Generic1
by Simon Peyton Jones 01 Jun '16

01 Jun '16

Ryan If you compile newtype Compose f g a = Compose (f (g a)) deriving( Generic1 ) and do –show-iface on the resulting hi file, you’ll see $fGeneric1Compose :: forall (f :: * -> *) k (g :: k -> *). Functor f => Generic1 (Compose f g) I was expecting to see $fGeneric1Compose :: forall (f :: k1 -> *) k (g :: k -> k1). (..something..) => Generic1 (Compose f g) Otherwise the Generic1 instance only works if its first argument has kind (* -> *). Is that the intention? Maybe so… Simon

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Core of a whole package
by Alberto Sadde O. 01 Jun '16

01 Jun '16

Hi, I am trying to get the Core of a whole package. I have been using the GHC API to get the Core of each file in a package but I have a problems with non-exposed modules of the package. I might not been setting up all the flags correctly but at this point I am completely lost!! I posted a question on S.O. <http://stackoverflow.com/questions/37410615/ghc-api-compile-whole-package-t…> The code I am using is in the above link. Any help/comments/tips would be greatly appreciated! Many thanks, Alberto

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Re: Strictness/laziness warnings
by David Feuer 30 May '16

30 May '16

Mostly I'm looking for a rough estimate. Some false positives and false negatives are tolerable. If I have something like f :: Int -> Maybe String -> String f _ Nothing = "Hi there!" f n (Just b) = if n > 0 then show b else "whatever" then I'd likely be interested in a warning about the fact that the first case is not strict in the Int and the second is. I'd also likely be interested in a warning about the first case because I'm taking a small primitive value (Int) and doing so lazily. On Sun, May 29, 2016 at 11:04 PM, wren romano <winterkoninkje(a)gmail.com> wrote: > On Sat, May 28, 2016 at 10:14 PM, Edward Kmett <ekmett(a)gmail.com> wrote: >> How would you detect the argument only being forced some of the time? Sounds >> like a lot of long-term cross-module book-keeping. > > Sounds to me like what the strictness analyzer is already doing, ne? I > missed the beginning of the thread, so might be off base. If it's more > about noticing when the use sites of a given function have some > pattern not captured by the strictness determined from the function's > definition, then it seems like we shouldn't need /cross/-module > bookkeeping: we should be able to just tabulate how each use site's > strictness does/doesn't match the interface's spec. > > -- > Live well, > ~wren

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GHC HEAD (built with itself) blows allocation stats :-(
by Gabor Greif 30 May '16

30 May '16

Hi devs, I get some pretty bad allocation statistics when testing GHC HEAD. Not sure why, but this is with a stage-0 compiler that is also GHC HEAD. (I doubt that that is the reason, though.) I see on a linux x64 system (RHEL6) : Unexpected stat failures: /tmp/ghctest/ayiNBP/1/2/3/./perf/compiler/T10370 T10370 [stat not good enough] (optasm) /tmp/ghctest/ayiNBP/1/2/3/./perf/compiler/T10547 T10547 [stat not good enough] (normal) /tmp/ghctest/ayiNBP/1/2/3/./perf/compiler/T1969 T1969 [stat not good enough] (normal) /tmp/ghctest/ayiNBP/1/2/3/./perf/compiler/T3064 T3064 [stat not good enough] (normal) /tmp/ghctest/ayiNBP/1/2/3/./perf/compiler/T3294 T3294 [stat not good enough] (normal) /tmp/ghctest/ayiNBP/1/2/3/./perf/compiler/T4801 T4801 [stat not good enough] (normal) /tmp/ghctest/ayiNBP/1/2/3/./perf/compiler/T5030 T5030 [stat not good enough] (normal) /tmp/ghctest/ayiNBP/1/2/3/./perf/compiler/T5321FD T5321FD [stat not good enough] (normal) /tmp/ghctest/ayiNBP/1/2/3/./perf/compiler/T5321Fun T5321Fun [stat not good enough] (normal) /tmp/ghctest/ayiNBP/1/2/3/./perf/compiler/T5631 T5631 [stat not good enough] (normal) /tmp/ghctest/ayiNBP/1/2/3/./perf/compiler/T5642 T5642 [stat not good enough] (normal) /tmp/ghctest/ayiNBP/1/2/3/./perf/compiler/T5837 T5837 [stat not good enough] (normal) /tmp/ghctest/ayiNBP/1/2/3/./perf/compiler/T6048 T6048 [stat not good enough] (optasm) /tmp/ghctest/ayiNBP/1/2/3/./perf/compiler/T783 T783 [stat not good enough] (normal) /tmp/ghctest/ayiNBP/1/2/3/./perf/compiler/T9020 T9020 [stat not good enough] (optasm) /tmp/ghctest/ayiNBP/1/2/3/./perf/compiler/T9233 T9233 [stat not good enough] (normal) /tmp/ghctest/ayiNBP/1/2/3/./perf/compiler/T9675 T9675 [stat not good enough] (optasm) /tmp/ghctest/ayiNBP/1/2/3/./perf/compiler/T9872a T9872a [stat not good enough] (normal) /tmp/ghctest/ayiNBP/1/2/3/./perf/compiler/T9872b T9872b [stat not good enough] (normal) /tmp/ghctest/ayiNBP/1/2/3/./perf/compiler/T9872c T9872c [stat not good enough] (normal) /tmp/ghctest/ayiNBP/1/2/3/./perf/compiler/T9872d T9872d [stat not good enough] (normal) /tmp/ghctest/ayiNBP/1/2/3/./perf/compiler/T9961 T9961 [stat not good enough] (normal) /tmp/ghctest/ayiNBP/1/2/3/./perf/compiler/parsing001 parsing001 [stat not good enough] (normal) /tmp/ghctest/ayiNBP/1/2/3/./perf/space_leaks/T4029 T4029 [stat not good enough] (ghci) Some of the tests look like this: cd /tmp/ghctest/ayiNBP/1/2/3/./perf/compiler/T9872a && "ghc-head-x86_64/inplace/test spaces/ghc-stage2" -c T9872a.hs -fforce-recomp -dno-debug-output -no-user-package-db -rtsopts -fno-warn-tabs -fno-warn-missed-specialisations -fshow-warning-groups -fno-ghci-history +RTS -V0 -tT9872a.comp.stats --machine-readable -RTS > T9872a.comp.stderr 2>&1 bytes allocated value is too high: Expected T9872a(normal) bytes allocated: 3352882080 +/-5% Lower bound T9872a(normal) bytes allocated: 3185237976 Upper bound T9872a(normal) bytes allocated: 3520526184 Actual T9872a(normal) bytes allocated: 13260131240 Deviation T9872a(normal) bytes allocated: 295.5 % *** unexpected stat test failure for T9872a(normal) Around 300% looks really bad. Can anybody reproduce this? For reference, this is the test command I run: $ make test TEST="T9961 T10547 T10370 T3064 T4029 T5642 parsing001 T783 T3294 T9872d T9872b T9872c T9872a T1969 T5321Fun T5837 T5631 T5321FD T5030 T4801 T6048 T9675 T9233 T9020" The testsuite works nicely otherwise. Cheers and thanks, Gabor

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comment lines in Cmm outputs
by Ömer Sinan Ağacan 29 May '16

29 May '16

I'm reading a lot of Cmm these days and comments added by Cmm dump (which are apparently added after 8.0.1) are so annoying becuase they're not saying anything useful (what's the point of adding "// CmmCall" to a "call" line or "// CmmCondBranch" to a "if" line?) but making a lot of noise. Why were those added? Can we remove them?

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Rank2Types example not typechecking w/ GHC8. Bug or feature?
by Michael Karg 29 May '16

29 May '16

Hi devs, could you please have a look at the following code snippet (modeled after a real-world app of mine)? There's a rank2type involved, and it doesn't type-check anymore when the type is e.g. part of a tuple, whereas everything's fine when it's the "outermost" type. With GHC7.10 both variants type-check. Could anyone shed some light on what's behind this? Is the way the types are used in the snippet considered dispreferred or wrong under GHC8? Thanks for having a look and hopefully pointing me to a page/ticket/... providing insight, Michael -------- {-# LANGUAGE Rank2Types #-} module TestTypes where data State a = State a data Dummy = Dummy type Handler result = forall state . State state -> IO result type Resolver = String -> Handler String eventRouter :: Resolver -> String -> IO () eventRouter resolver event = resolver event state >> return () where state :: State () state = undefined {- -- does type check createResolver :: Resolver createResolver = \event state -> return "result" processor :: IO () processor = getLine >>= eventRouter resolver >> processor where resolver = createResolver -} -- does not type check when the rank 2 type isn't the "outermost" one? createResolver :: (Resolver, Dummy) createResolver = (\event state -> return "result", Dummy) processor :: IO () processor = getLine >>= eventConsumer resolver >> processor where (resolver, _) = createResolver {- • Couldn't match type ‘t’ with ‘Resolver’ ‘t’ is a rigid type variable bound by the inferred type of resolver :: t at TestTypes.hs:41:5 Expected type: (t, Dummy) Actual type: (Resolver, Dummy) -}

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real person believed to be a spambot
by Richard Eisenberg 29 May '16

29 May '16

Hi devs, I'm forwarding the following from a friend (cc'd) who was unable to register for Trac. Can anyone help? ---- Hi. I tried to register with username "j6carey" and email "j6carey(a)gmail.com" to report a bug in GHC 8.0.1, and the system says there's a 97% chance I'm a spammer. It asked me a question first ("What does the G stand for in GHC?"), and I thought I answered correctly, in lowercase as requested, but it still rejected me, and now it won't even ask that question again (for the same browser, at least). Do you know what's going wrong?

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Strictness/laziness warnings
by David Feuer 29 May '16

29 May '16

There are certain patterns of strictness or laziness that signal the need for extra caution. I'm wondering whether it might be possible to offer warnings for different varieties of them, and pragmas suppressing the warnings at the relevant sites. Some function behaviors that suggest extra care: 1. Conditionally strict in an argument. In many cases, making it unconditionally strict will improve performance. 2. Strict in an argument that is or could be a function or a newtype wrapper around a function. This can be caused by adding too much strictness defensively or to plug a leak. 3. Lazy in a primitive argument like an Int. This could lead to unnecessary boxing. Any of these could occur in correct, efficient code. But I'd love to be presented a list of warnings to check over, and a way to check items off the list with pragmas.

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Unpacking single-field, single-strict-constructor GADTs and existentials
by David Feuer 29 May '16

29 May '16

Data.IntMap could be cleaned up some if single-field, single strict constructor GADTs/existentials could be unpacked even when wrapping a sum type. We could then have data Status = E | NE data IntMap' (s :: Status) a where Bin :: ... -> ... -> !(IntMap' NE a) -> !(IntMap' NE a) -> IntMap' NE a Tip :: ... -> a -> IntMap' NE a Nil :: IntMap' E a data IntMap a = forall s . IM {-# UNPACK #-} !(IntMap' s a) The representation would be the same as that of a newtype, but the pattern matching semantics would be strict. In the GADT case, this would essentially allow any fixed concrete datatype to serve directly as a witness for an arbitrary set of type equalities demanded on construction. Is there any hope something like this could happen?

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can't build with release settings
by Ömer Sinan Ağacan 28 May '16

28 May '16

Is anyone else having this problem when building with default settings (no build.mk): "inplace/bin/ghc-stage2" -hisuf dyn_hi -osuf dyn_o -hcsuf dyn_hc -fPIC -dynamic -H32m -O -Wall -hide-all-packages -i -iutils/haddock/driver -iutils/haddock/haddock-api/src -iutils/haddock/haddock-library/vendor/attoparsec-0.12.1.1 -iutils/haddock/haddock-library/src -iutils/haddock/dist/build -iutils/haddock/dist/build/autogen -Iutils/haddock/dist/build -Iutils/haddock/dist/build/autogen -optP-DIN_GHC_TREE -optP-include -optPutils/haddock/dist/build/autogen/cabal_macros.h -package-id Cabal-1.25.0.0 -package-id array-0.5.1.1 -package-id base-4.9.0.0 -package-id bytestring-0.10.8.1 -package-id containers-0.5.7.1 -package-id deepseq-1.4.2.0 -package-id directory-1.2.6.2 -package-id filepath-1.4.1.0 -package-id ghc-8.1 -package-id ghc-boot-8.1 -package-id transformers-0.5.2.0 -package-id xhtml-3000.2.1 -funbox-strict-fields -Wall -fwarn-tabs -O2 -threaded -XHaskell2010 -no-user-package-db -rtsopts -Wno-unused-imports -Wno-deprecations -Wnoncanonical-monad-instances -odir utils/haddock/dist/build -hidir utils/haddock/dist/build -stubdir utils/haddock/dist/build -c utils/haddock/haddock-library/src/Documentation/Haddock/Types.hs -o utils/haddock/dist/build/Documentation/Haddock/Types.dyn_o utils/haddock/haddock-library/src/Documentation/Haddock/Types.hs:15:8: error: Failed to load interface for ‘Prelude’ It is a member of the hidden package ‘base-4.9.0.0’. Use -v to see a list of the files searched for. utils/haddock/haddock-library/src/Documentation/Haddock/Types.hs:17:1: error: Failed to load interface for ‘Data.Foldable’ It is a member of the hidden package ‘base-4.9.0.0’. Use -v to see a list of the files searched for. utils/haddock/haddock-library/src/Documentation/Haddock/Types.hs:18:1: error: Failed to load interface for ‘Data.Traversable’ It is a member of the hidden package ‘base-4.9.0.0’. Use -v to see a list of the files searched for. utils/haddock/driver/ResponseFile.hs:2:8: error: Failed to load interface for ‘Prelude’ It is a member of the hidden package ‘base-4.9.0.0’. Use -v to see a list of the files searched for. utils/haddock/driver/ResponseFile.hs:8:1: error: Failed to load interface for ‘Control.Exception’ It is a member of the hidden package ‘base-4.9.0.0’. Use -v to see a list of the files searched for. utils/haddock/driver/ResponseFile.hs:9:1: error: Failed to load interface for ‘Data.Char’ It is a member of the hidden package ‘base-4.9.0.0’. Use -v to see a list of the files searched for. utils/haddock/driver/ResponseFile.hs:10:1: error: Failed to load interface for ‘Data.Foldable’ It is a member of the hidden package ‘base-4.9.0.0’. Use -v to see a list of the files searched for. utils/haddock/driver/ResponseFile.hs:11:1: error: Failed to load interface for ‘System.Exit’ It is a member of the hidden package ‘base-4.9.0.0’. Use -v to see a list of the files searched for. utils/haddock/driver/ResponseFile.hs:12:1: error: Failed to load interface for ‘System.IO’ It is a member of the hidden package ‘base-4.9.0.0’. Use -v to see a list of the files searched for. utils/haddock/haddock-api/src/Haddock/GhcUtils.hs:16:8: error:utils/haddock/haddock-api/src/Haddock/Backends/Hyperlinker/Types.hs:1:8: error: Failed to load interface for ‘Prelude’ It is a member of the hidden package Failed to load interface for ‘base-4.9.0.0’. Use -v to see a list of the files searched for. ‘Prelude’ It is a member of the hidden package ‘base-4.9.0.0’. Use -v to see a list of the files searched for. utils/haddock/haddock-api/src/Haddock/GhcUtils.hs:19:1: error: Failed to load interface for ‘Control.Arrow’ It is a member of the hidden package ‘base-4.9.0.0’. Use -v to see a list of the files searched for. utils/haddock/haddock-api/src/Haddock/Backends/Hyperlinker/Types.hs:4:1: error:utils/haddock/haddock-api/src/Haddock/GhcUtils.hs:20:1: error: Failed to load interface for Failed to load interface for ‘GHC’ ‘Data.Function’ It is a member of the hidden package It is a member of the hidden package ‘base-4.9.0.0’. ‘ghc-8.1’. Use -v to see a list of the files searched for. Use -v to see a list of the files searched for. utils/haddock/haddock-api/src/Haddock/GhcUtils.hs:22:1: error: Failed to load interface for ‘Exception’ It is a member of the hidden package ‘ghc-8.1’. Use -v to see a list of the files searched for. utils/haddock/haddock-api/src/Haddock/GhcUtils.hs:23:1: error: Failed to load interface for ‘Outputable’ It is a member of the hidden package ‘ghc-8.1’. Use -v to see a list of the files searched for. utils/haddock/haddock-api/src/Haddock/GhcUtils.hs:24:1: error: Failed to load interface for ‘Name’ It is a member of the hidden package ‘ghc-8.1’. Use -v to see a list of the files searched for. utils/haddock/haddock-api/src/Haddock/GhcUtils.hs:25:1: error: Failed to load interface for ‘Lexeme’ It is a member of the hidden package ‘ghc-8.1’. Use -v to see a list of the files searched for. utils/haddock/haddock-api/src/Haddock/GhcUtils.hs:26:1: error: Failed to load interface for ‘Module’ It is a member of the hidden package ‘ghc-8.1’. Use -v to see a list of the files searched for. utils/haddock/haddock-api/src/Haddock/GhcUtils.hs:27:1: error: Failed to load interface for ‘RdrName’ It is a member of the hidden package ‘ghc-8.1’. Use -v to see a list of the files searched for. utils/haddock/haddock-api/src/Haddock/GhcUtils.hs:28:1: error: Failed to load interface for ‘GhcMonad’ It is a member of the hidden package ‘ghc-8.1’. Use -v to see a list of the files searched for. utils/haddock/haddock-api/src/Haddock/GhcUtils.hs:29:1: error: Failed to load interface for ‘HscTypes’ It is a member of the hidden package ‘ghc-8.1’. Use -v to see a list of the files searched for. utils/haddock/haddock-api/src/Haddock/GhcUtils.hs:30:1: error: Failed to load interface for ‘UniqFM’ It is a member of the hidden package ‘ghc-8.1’. Use -v to see a list of the files searched for. utils/haddock/haddock-api/src/Haddock/GhcUtils.hs:31:1: error: Failed to load interface for ‘GHC’ It is a member of the hidden package ‘ghc-8.1’. Use -v to see a list of the files searched for. utils/haddock/haddock-api/src/Haddock/GhcUtils.hs:32:1: error: Failed to load interface for ‘Class’ It is a member of the hidden package ‘ghc-8.1’. Use -v to see a list of the files searched for. utils/haddock/ghc.mk:21: recipe for target 'utils/haddock/dist/build/ResponseFile.dyn_o' failed make[1]: *** [utils/haddock/dist/build/ResponseFile.dyn_o] Error 1 make[1]: *** Waiting for unfinished jobs.... utils/haddock/ghc.mk:21: recipe for target 'utils/haddock/dist/build/Documentation/Haddock/Types.dyn_o' failed make[1]: *** [utils/haddock/dist/build/Documentation/Haddock/Types.dyn_o] Error 1 utils/haddock/ghc.mk:21: recipe for target 'utils/haddock/dist/build/Haddock/Backends/Hyperlinker/Types.dyn_o' failed make[1]: *** [utils/haddock/dist/build/Haddock/Backends/Hyperlinker/Types.dyn_o] Error 1 utils/haddock/ghc.mk:21: recipe for target 'utils/haddock/dist/build/Haddock/GhcUtils.dyn_o' failed make[1]: *** [utils/haddock/dist/build/Haddock/GhcUtils.dyn_o] Error 1 Makefile:129: recipe for target 'all' failed make: *** [all] Error 2 ( make distclean && ./boot && ./configure && make -j4; ) 2>&1 6382.95s user 1069.99s system 336% cpu 36:57.03 total tee build_output 0.04s user 0.60s system 0% cpu 36:57.03 total This is d40682e + one commit that I'm sure wouldn't break the build this way. I can't compile anything with stage2 compiler becuase of this: ➜ strict_cmm ghc-stage2 Main.hs [1 of 1] Compiling Lib ( Main.hs, Main.o ) [Prelude changed] Main.hs:4:1: error: Failed to load interface for ‘Prelude’ It is a member of the hidden package ‘base-4.9.0.0’. Use -v to see a list of the files searched for. -v output: ➜ strict_cmm ghc-stage2 Main.hs -v Glasgow Haskell Compiler, Version 8.1.20160528, stage 2 booted by GHC version 8.0.1 Using binary package database: /home/omer/haskell/ghc_3/inplace/lib/package.conf.d/package.cache loading package database /home/omer/haskell/ghc_3/inplace/lib/package.conf.d wired-in package ghc-prim mapped to ghc-prim-0.5.0.0 wired-in package integer-gmp mapped to integer-gmp-1.0.0.1 wired-in package base mapped to base-4.9.0.0 wired-in package rts mapped to rts wired-in package template-haskell mapped to template-haskell-2.11.0.0 wired-in package ghc mapped to ghc-8.1 wired-in package dph-seq not found. wired-in package dph-par not found. Hsc static flags: loading package database /home/omer/haskell/ghc_3/inplace/lib/package.conf.d wired-in package ghc-prim mapped to ghc-prim-0.5.0.0 wired-in package integer-gmp mapped to integer-gmp-1.0.0.1 wired-in package base mapped to base-4.9.0.0 wired-in package rts mapped to rts-1.0 wired-in package template-haskell mapped to template-haskell-2.11.0.0 wired-in package ghc mapped to ghc-8.1 wired-in package dph-seq not found. wired-in package dph-par not found. *** Chasing dependencies: Chasing modules from: *Main.hs !!! Chasing dependencies: finished in 0.44 milliseconds, allocated 0.417 megabytes Stable obj: [Lib] Stable BCO: [] Ready for upsweep [NONREC ModSummary { ms_hs_date = 2016-05-28 13:53:06.703533428 UTC ms_mod = Lib, ms_textual_imps = [(Nothing, Prelude)] ms_srcimps = [] }] *** Deleting temp files: Deleting: compile: input file Main.hs *** Checking old interface for Lib: [1 of 1] Compiling Lib ( Main.hs, Main.o ) [Prelude changed] *** Parser [Lib]: !!! Parser [Lib]: finished in 0.42 milliseconds, allocated 0.466 megabytes *** Renamer/typechecker [Lib]: !!! Renamer/typechecker [Lib]: finished in 0.05 milliseconds, allocated 0.004 megabytes Main.hs:4:1: error: Failed to load interface for ‘Prelude’ It is a member of the hidden package ‘base-4.9.0.0’. Locations searched: Prelude.hs Prelude.lhs Prelude.hsig Prelude.lhsig Upsweep partially successful. *** Deleting temp files: Deleting: link(batch): upsweep (partially) failed OR Main.main not exported; not linking. *** Deleting temp files: Deleting: *** Deleting temp dirs: Deleting: Any ideas?

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