October 2015 - ghc-devs

Documenting record pattern synonyms
by Simon Peyton Jones 30 Oct '15

30 Oct '15

Matthew: Could you please write the user-manual sections that you have promised? That is, the *specification* this feature. Currently, so far as I can see, there is literally NO user manual documentation. No changes to docs/users_guide whatsoever. We have discussed this on several occasions, and you agreed to do it. I sat with you in person and showed you what I have in mind. There is a sketch on the wiki page. I did not intend this patch to land until the user documentation was done. Now I feel as if I've lost my leverage :-). But it really really really really needs doing. Please. I'm begging you. Compared to what you have already done, it's easy. Simon | -----Original Message----- | From: ghc-commits [mailto:ghc-commits-bounces@haskell.org] On Behalf Of | git(a)git.haskell.org | Sent: 29 October 2015 11:25 | To: ghc-commits(a)haskell.org | Subject: [commit: ghc] master: Record pattern synonyms (2a74a64) | | Repository : ssh://git@git.haskell.org/ghc | | On branch : master | Link : | https://na01.safelinks.protection.outlook.com/?url=http%3a%2f%2fghc.haskell. | org%2ftrac%2fghc%2fchangeset%2f2a74a64e8329ab9e0c74bec47198cb492d25affb%2fgh | c&data=01%7c01%7csimonpj%40064d.mgd.microsoft.com%7c0deecf24e85641ff3abb08d2 | e05387f2%7c72f988bf86f141af91ab2d7cd011db47%7c1&sdata=nEAgwVmvFQNgN%2bANGD4H | z1flN%2fucKSRFoZMdhRqQKSM%3d | | >--------------------------------------------------------------- | | commit 2a74a64e8329ab9e0c74bec47198cb492d25affb | Author: Matthew Pickering <matthewtpickering(a)gmail.com> | Date: Mon Oct 19 21:17:29 2015 +0100 | | Record pattern synonyms | | This patch implements an extension to pattern synonyms which allows user | to specify pattern synonyms using record syntax. Doing so generates | appropriate selectors and update functions. | | === Interaction with Duplicate Record Fields === | | The implementation given here isn't quite as general as it could be with | respect to the recently-introduced `DuplicateRecordFields` extension. | | Consider the following module: | | {-# LANGUAGE DuplicateRecordFields #-} | {-# LANGUAGE PatternSynonyms #-} | | module Main where | | pattern S{a, b} = (a, b) | pattern T{a} = Just a | | main = do | print S{ a = "fst", b = "snd" } | print T{ a = "a" } | | In principle, this ought to work, because there is no ambiguity. But at | the moment it leads to a "multiple declarations of a" error. The problem | is that pattern synonym record selectors don't do the same name mangling | as normal datatypes when DuplicateRecordFields is enabled. They could, | but this would require some work to track the field label and selector | name separately. | | In particular, we currently represent datatype selectors in the third | component of AvailTC, but pattern synonym selectors are just represented | as Avails (because they don't have a corresponding type constructor). | Moreover, the GlobalRdrElt for a selector currently requires it to have | a parent tycon. | | (example due to Adam Gundry) | | === Updating Explicitly Bidirectional Pattern Synonyms === | | Consider the following | | ``` | pattern Silly{a} <- [a] where | Silly a = [a, a] | | f1 = a [5] -- 5 | | f2 = [5] {a = 6} -- currently [6,6] | ``` | | === Fixing Polymorphic Updates === | | They were fixed by adding these two lines in `dsExpr`. This might break | record updates but will be easy to fix. | | ``` | + ; let req_wrap = mkWpTyApps (mkTyVarTys univ_tvs) | | - , pat_wrap = idHsWrapper } | +, pat_wrap = req_wrap } | ``` | | === Mixed selectors error === | | Note [Mixed Record Field Updates] | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | | Consider the following pattern synonym. | | data MyRec = MyRec { foo :: Int, qux :: String } | | pattern HisRec{f1, f2} = MyRec{foo = f1, qux=f2} | | This allows updates such as the following | | updater :: MyRec -> MyRec | updater a = a {f1 = 1 } | | It would also make sense to allow the following update (which we | reject). | | updater a = a {f1 = 1, qux = "two" } ==? MyRec 1 "two" | | This leads to confusing behaviour when the selectors in fact refer the | same field. | | updater a = a {f1 = 1, foo = 2} ==? ??? | | For this reason, we reject a mixture of pattern synonym and normal | record selectors in the same update block. Although of course we still | allow the following. | | updater a = (a {f1 = 1}) {foo = 2} | | > updater (MyRec 0 "str") | MyRec 2 "str" | | | >--------------------------------------------------------------- | | 2a74a64e8329ab9e0c74bec47198cb492d25affb | compiler/basicTypes/ConLike.hs | 86 +++++++- | compiler/basicTypes/ConLike.hs-boot | 18 ++ | compiler/basicTypes/Id.hs | 31 ++- | compiler/basicTypes/IdInfo.hs | 21 +- | compiler/basicTypes/PatSyn.hs | 51 +++-- | compiler/deSugar/Coverage.hs | 11 +- | compiler/deSugar/DsExpr.hs | 79 ++++--- | compiler/deSugar/DsMeta.hs | 2 +- | compiler/hsSyn/Convert.hs | 10 +- | compiler/hsSyn/HsBinds.hs | 67 +++++- | compiler/hsSyn/HsExpr.hs | 35 +++- | compiler/hsSyn/HsUtils.hs | 21 +- | compiler/hsSyn/PlaceHolder.hs | 6 +- | compiler/iface/BuildTyCl.hs | 7 +- | compiler/iface/IfaceSyn.hs | 17 +- | compiler/iface/MkIface.hs | 11 +- | compiler/iface/TcIface.hs | 12 +- | compiler/main/HscTypes.hs | 15 +- | compiler/parser/Parser.y | 28 ++- | compiler/parser/RdrHsSyn.hs | 2 +- | compiler/prelude/TysWiredIn.hs | 2 +- | compiler/rename/RnBinds.hs | 18 +- | compiler/rename/RnExpr.hs | 8 +- | compiler/rename/RnNames.hs | 30 +-- | compiler/rename/RnSource.hs | 52 ++++- | compiler/typecheck/TcBinds.hs | 6 +- | compiler/typecheck/TcExpr.hs | 231 +++++++++++++++--- | --- | compiler/typecheck/TcHsSyn.hs | 10 +- | compiler/typecheck/TcPat.hs | 6 +- | compiler/typecheck/TcPatSyn.hs | 124 ++++++++--- | compiler/typecheck/TcPatSyn.hs-boot | 8 +- | compiler/typecheck/TcRnDriver.hs | 3 +- | compiler/typecheck/TcTyClsDecls.hs | 39 ++-- | compiler/types/TyCon.hs | 7 +- | compiler/types/TypeRep.hs | 2 +- | compiler/types/TypeRep.hs-boot | 1 + | testsuite/tests/patsyn/should_compile/all.T | 7 +- | .../tests/patsyn/should_compile/records-compile.hs | 11 + | .../tests/patsyn/should_compile/records-poly.hs | 16 ++ | .../patsyn/should_compile/records-prov-req.hs | 26 +++ | .../patsyn/should_compile/records-req-only.hs | 16 ++ | .../tests/patsyn/should_compile/records-req.hs | 14 ++ | testsuite/tests/patsyn/should_fail/all.T | 7 + | .../should_fail/mixed-pat-syn-record-sels.hs | 9 + | .../should_fail/mixed-pat-syn-record-sels.stderr | 5 + | .../tests/patsyn/should_fail/records-check-sels.hs | 10 + | .../patsyn/should_fail/records-check-sels.stderr | 3 + | .../tests/patsyn/should_fail/records-exquant.hs | 10 + | .../patsyn/should_fail/records-exquant.stderr | 11 + | .../patsyn/should_fail/records-mixing-fields.hs | 12 ++ | .../should_fail/records-mixing-fields.stderr | 17 ++ | .../patsyn/should_fail/records-no-uni-update.hs | 7 + | .../should_fail/records-no-uni-update.stderr | 5 + | .../patsyn/should_fail/records-no-uni-update2.hs | 11 + | .../should_fail/records-no-uni-update2.stderr | 5 + | .../patsyn/should_fail/records-poly-update.hs | 13 ++ | .../patsyn/should_fail/records-poly-update.stderr | 5 + | testsuite/tests/patsyn/should_run/all.T | 1 + | testsuite/tests/patsyn/should_run/records-run.hs | 14 ++ | .../tests/patsyn/should_run/records-run.stdout | 5 + | 60 files changed, 1055 insertions(+), 262 deletions(-) | | Diff suppressed because of size. To see it, use: | | git diff-tree --root --patch-with-stat --no-color --find-copies-harder - | -ignore-space-at-eol --cc 2a74a64e8329ab9e0c74bec47198cb492d25affb | _______________________________________________ | ghc-commits mailing list | ghc-commits(a)haskell.org | https://na01.safelinks.protection.outlook.com/?url=http%3a%2f%2fmail.haskell | .org%2fcgi-bin%2fmailman%2flistinfo%2fghc- | commits&data=01%7c01%7csimonpj%40064d.mgd.microsoft.com%7c0deecf24e85641ff3a | bb08d2e05387f2%7c72f988bf86f141af91ab2d7cd011db47%7c1&sdata=ymzeKEsSAnOhr4QL | ngFKt0e8B84voue20%2bCyMPwWf%2fQ%3d

2 2

Re: Type-level error messages
by Richard Eisenberg 29 Oct '15

29 Oct '15

On Oct 28, 2015, at 10:02 AM, "Augustsson, Lennart" <Lennart.Augustsson(a)sc.com> wrote: > I've put in my answers to your questions. And I've responded.

3 3

RE: Compiling without -O
by Simon Peyton Jones 29 Oct '15

29 Oct '15

I suspect you are trying to run 'make 1' after a validate failure, and those settings don't get applied. I have put https://phabricator.haskell.org/D1383 up for review to bring 'mk/are-validating.mk<https://na01.safelinks.protection.outlook.com/?url=http%3a%2f%2fare-validat…>' back, which should fix that. Correct! I can’t wait ☺ Simon From: Thomas Miedema [mailto:thomasmiedema@gmail.com] Sent: 29 October 2015 11:43 To: Simon Peyton Jones Subject: Re: Compiling without -O validate uses options from mk/validate.mk<https://na01.safelinks.protection.outlook.com/?url=http%3a%2f%2fvalidate.mk…> as always. Nothing should have changed there. You say it doesn't work anymore. How do you know? I suspect you are trying to run 'make 1' after a validate failure, and those settings don't get applied. I have put https://phabricator.haskell.org/D1383 up for review to bring 'mk/are-validating.mk<https://na01.safelinks.protection.outlook.com/?url=http%3a%2f%2fare-validat…>' back, which should fix that. On Thu, Oct 29, 2015 at 12:10 PM, Simon Peyton Jones <simonpj(a)microsoft.com<mailto:simonpj@microsoft.com>> wrote: I want to validate, but to compile my stage-1 compiler with –O0. How do I do that? I used to add GhcStage1HcOpts += -DDEBUG -O0 to mk/validate.mk<https://na01.safelinks.protection.outlook.com/?url=http%3a%2f%2fvalidate.mk…>, but that doesn’t seem to work any more. What now? Simon _______________________________________________ ghc-devs mailing list ghc-devs(a)haskell.org<mailto:ghc-devs@haskell.org> http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs<https://na01.safelinks.protection.outlook.com/?url=http%3a%2f%2fmail.haskel…>

2 1

Compiling without -O
by Simon Peyton Jones 29 Oct '15

29 Oct '15

I want to validate, but to compile my stage-1 compiler with -O0. How do I do that? I used to add GhcStage1HcOpts += -DDEBUG -O0 to mk/validate.mk, but that doesn't seem to work any more. What now? Simon

1 0

Temporarily pinning a thread to a capability
by Edward Kmett 28 Oct '15

28 Oct '15

Would anything go wrong with a thread id if I pinned it to a capability after the fact? I could in theory do so just by setting tso->flags |= TSO_LOCKED and then disabling this later by restoring the TSO flags. I can't think of anything but I figured folks here might be able to think of invariants I don't know about. Usage scenario: I have a number of things where I can't afford a map from a ThreadId# or even its internal id to a per-thread value for bounded wait-free structures. On the other hand, I can afford one entry per capability and to make a handful of primitives that can't be preempted, letting me use normal writes, not even a CAS, to update the capability-local variable in a primitive (indexing into an array of size based on the number of capabilities). This lets me bound the amount of "helpers" to consider by the capability count rather than the potentially much larger and much more variable number of live threads. However, I may need to access this stuff in "pure" code that wasn't written with my needs in mind, so I need to at least temporarily pin the current thread to a fixed capability for the duration when that happens. This isn't perfect, it won't react to a growing number of capabilities nicely in the future, but it does handle a lot of things I can't do now at all without downgrading to lock-free and starving a lot of computations, so I'm hoping the answer is "it all works". =) -Edward

3 4

GADT decls
by Simon Peyton Jones 28 Oct '15

28 Oct '15

Ahh. I think I get it. The trouble is that ConDecl doesn’t have the same structure as what the user wrote. Maybe we should just fix that? How about this declaration? Would that make the annotations easier? Ie simple and routine. Simon data ConDecl name | ConDeclGADT { con_names :: [Located name] , con_type :: LHsSigType name -- After the ‘::’ , con_doc :: Maybe LHsDocString , con_old_rec :: Bool } | ConDeclH98 { con_name :: Located name , con_implict :: HsImplicitBndrs () -- ^ Implicit binders, added by renamer , con_qvars :: Maybe [LHsTyVarBndr name] -- User-written foralls (if any) , con_cxt :: Maybe (LHsContext name) -- ^ User-written context (if any) , con_details :: HsConDeclDetails name -- ^ Arguments , con_doc :: Maybe LHsDocString -- ^ A possible Haddock comment. } deriving (Typeable) From: Alan & Kim Zimmerman [mailto:alan.zimm@gmail.com] Sent: 27 October 2015 21:36 To: Simon Peyton Jones Subject: Re: dll-split The problem comes in mkGadtDecl, I am pretty sure. If I compare your branch to master, I see that the old one was mkGadtDecl :: [Located RdrName] -> LHsType RdrName -- Always a HsForAllTy -> P ([AddAnn], ConDecl RdrName) mkGadtDecl names (L l ty) = do let (anns,ty') = flattenHsForAllTyKeepAnns ty gadt <- mkGadtDecl' names (L l ty') return (anns,gadt) where the flattenHsForAllTyKeepAnns explicitly pulls out annotations that will get lost when the original type gets broken apart and re-assembled as a ConDecl for the GADT. I do recall having to exercise particular care in this area the first time around, because of the way the original type is turned into a GADT constructor. If this does not help, I can try and dive into what you are doing in more detail tomorrow afternoon some time. Alan On Tue, Oct 27, 2015 at 11:22 PM, Simon Peyton Jones <simonpj(a)microsoft.com<mailto:simonpj@microsoft.com>> wrote: Thanks. But why?! Here’s my reasoning, looking at Parser.y • The RHS of the GADT signature is a ‘ctype’ • That parses the “forall v a.” , and then goes to type, then btype, then atype • Now we get to the production ‘(‘ ctype ‘)’ in atype • And that has mop and mcp to record the location of the parens. It all looks right to me. But NB that now HsForAllTy and HsQualTy are split, so the parens will be attached to the HsQualTy sub-structure. Does that make a difference? Simon From: Alan & Kim Zimmerman [mailto:alan.zimm@gmail.com<mailto:alan.zimm@gmail.com>] Sent: 27 October 2015 21:04 To: Simon Peyton Jones Subject: Re: dll-split I have run the tests on your branch, and can report the following for the failing API annotations tests . T10268 [bad stdout] (normal) - Benign . T10354 [bad stdout] (normal) - Benign . T10396 [bad stdout] (normal) - Benign . T10399 [bad stdout] (normal) - Problem . listcomps [bad stdout] (normal) - Benign For T10399 the problem is the following are missing (AK Test10399.hs:(16,5)-(17,69) AnnCloseP = [Test10399.hs:17:69]) (AK Test10399.hs:(16,5)-(17,69) AnnOpenP = [Test10399.hs:16:27]) These are the outer parens in SetTo4 after the forall : data MaybeDefault v where SetTo :: forall v . ( Eq v, Show v ) => !v -> MaybeDefault v SetTo4 :: forall v a. (( Eq v, Show v ) => v -> MaybeDefault v -> a -> MaybeDefault [a]) I will be documenting the check-api-annotations usage soon, and as part of that will clean it up so that it does not emit gratuitous changes that are benign. Regards Alan On Tue, Oct 27, 2015 at 11:21 AM, Simon Peyton Jones <simonpj(a)microsoft.com<mailto:simonpj@microsoft.com>> wrote: Incidentally, Alan, on this particular branch I have some api-annotations failures that I can’t figure out (lacking the user manual that you are writing). I wonder if you could help. Could you possibly build that branch for yourself too? wip/spj-wildcard-refactor Then I can ask you specifics and you’ll have a working branch to poke at. Thanks! Simon From: Alan & Kim Zimmerman [mailto:alan.zimm@gmail.com<mailto:alan.zimm@gmail.com>] Sent: 27 October 2015 09:12 To: Simon Peyton Jones Cc: ghc-devs(a)haskell.org<mailto:ghc-devs@haskell.org>; Ben Gamari Subject: Re: dll-split I think you need to remove Ctype and Lexer from https://github.com/ghc/ghc/blob/master/compiler/ghc.mk#L498<https://na01.safelinks.protection.outlook.com/?url=https%3a%2f%2fgithub.com…> On 27 Oct 2015 11:06 AM, "Simon Peyton Jones" <simonpj(a)microsoft.com<mailto:simonpj@microsoft.com>> wrote: It’s just not my day. Now, on Linux, on my branch wip/spj-wildcard-refactor, I get a failure in dll-split! Should dll-split be running at all on Linux???? The output it produces is below. I’m totally stuck. Help desperately needed. Simon inplace/bin/dll-split compiler/stage2/build/.depend-v-p-dyn.haskell "DynFlags" "Annotations ApiAnnotation Avail Bag BasicTypes Binary BooleanFormula BreakArray BufWrite Class CmdLineParser CmmType CoAxiom ConLike Coercion Config Constants CoreArity CoreFVs CoreSubst CoreSyn CoreTidy CoreUnfold CoreUtils CoreSeq CoreStats CostCentre Ctype DataCon Demand Digraph DriverPhases DynFlags Encoding ErrUtils Exception FamInstEnv FastFunctions FastMutInt FastString FastStringEnv FieldLabel Fingerprint FiniteMap ForeignCall Hooks HsBinds HsDecls HsDoc HsExpr HsImpExp HsLit PlaceHolder HsPat HsSyn HsTypes HsUtils HscTypes IOEnv Id IdInfo IfaceSyn IfaceType InstEnv Kind Lexeme Lexer ListSetOps Literal Maybes MkCore MkId Module MonadUtils Name NameEnv NameSet OccName OccurAnal OptCoercion OrdList Outputable PackageConfig Packages Pair Panic PatSyn PipelineMonad Platform PlatformConstants PprCore PrelNames PrelRules Pretty PrimOp RdrName Rules Serialized SrcLoc StaticFlags StringBuffer TcEvidence TcRnTypes TcType TrieMap TyCon Type TypeRep TysPrim TysWiredIn Unify UniqFM UniqSet UniqSupply Unique Util Var VarEnv VarSet Bitmap BlockId ByteCodeAsm ByteCodeInstr ByteCodeItbls CLabel Cmm CmmCallConv CmmExpr CmmInfo CmmMachOp CmmNode CmmSwitch CmmUtils CodeGen.Platform CodeGen.Platform.ARM CodeGen.Platform.ARM64 CodeGen.Platform.NoRegs CodeGen.Platform.PPC CodeGen.Platform.PPC_Darwin CodeGen.Platform.SPARC CodeGen.Platform.X86 CodeGen.Platform.X86_64 Hoopl Hoopl.Dataflow InteractiveEvalTypes MkGraph PprCmm PprCmmDecl PprCmmExpr Reg RegClass SMRep StgCmmArgRep StgCmmClosure StgCmmEnv StgCmmLayout StgCmmMonad StgCmmProf StgCmmTicky StgCmmUtils StgSyn Stream" Reachable modules from DynFlags out of date Please fix compiler/ghc.mk<https://na01.safelinks.protection.outlook.com/?url=http%3a%2f%2fghc.mk&data…>, or building DLLs on Windows may break (#7780) Redundant modules: Ctype Lexer simonpj@cam-05-unx:~/5builds/HEAD-2$ _______________________________________________ ghc-devs mailing list ghc-devs(a)haskell.org<mailto:ghc-devs@haskell.org> http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs<https://na01.safelinks.protection.outlook.com/?url=http%3a%2f%2fmail.haskel…>

2 1

RE: Type-level error messages
by Simon Peyton Jones 28 Oct '15

28 Oct '15

I’ve forgotten the state of your type-level error messages work. How’s it going? I think we should try to add it to 8.0.1. The current status is that the idea is implemented on a branch. Then, there were some comments and suggestions that maybe we should do things in a different way, implementation wise. I haven't had a chance to look into these in detail, or implement them, and as far as I know nobody else has stepped up to make the changes. So we could simply go with the current version, and if for some reason we want to change the implementation we could do it later, as I don't think the API will be affected in any way. When do the changes need to happen by, so that it makes it in 8.0? I have been a bit busy, but I could probably find some time to make whatever changes are required for this to be merged. OK good! In that case · Add it to the hoped-for features in the GHC 8.01. status page · Write a wiki page with a specification · Announce the proposal and seek feedback · Meanwhile make sure the branch reflects what you want to be in it If you don’t have time, well, no harm done… any progress you make on the above will still be useful. Simon From: Iavor Diatchki [mailto:iavor.diatchki@gmail.com] Sent: 22 October 2015 17:42 To: Simon Peyton Jones Cc: Augustsson, Lennart Subject: Re: Type-level error messages Hello, I think we should try to add it to 8.0.1. The current status is that the idea is implemented on a branch. Then, there were some comments and suggestions that maybe we should do things in a different way, implementation wise. I haven't had a chance to look into these in detail, or implement them, and as far as I know nobody else has stepped up to make the changes. So we could simply go with the current version, and if for some reason we want to change the implementation we could do it later, as I don't think the API will be affected in any way. When do the changes need to happen by, so that it makes it in 8.0? I have been a bit busy, but I could probably find some time to make whatever changes are required for this to be merged. -Iavor On Thu, Oct 22, 2015 at 3:47 AM, Simon Peyton Jones <simonpj(a)microsoft.com<mailto:simonpj@microsoft.com>> wrote: Iavor I’ve forgotten the state of your type-level error messages work. How’s it going? It’s not mentioned on https://ghc.haskell.org/trac/ghc/wiki/Status/GHC-8.0.1: shouldn’t it be? Simon

5 8

dns issues with ghc.haskell.org
by lennart spitzner 27 Oct '15

27 Oct '15

hi, This mail is intended for the maintainers of ghc.haskell.org who i can hopefully reach on this list. Once more i run into the issue that firefox resolves ghc.haskell.org to the wrong (an outdated?) ip address (resulting in some 500 Internal Server Error page; i guess on some other server..). When switching to a different browser the address is resolved "correctly" and i reach the expected server. For me personally this is only slightly annoying, but another fellow on irc recently reported the same symptoms, so i am not the only one affected. Might be worth resolving. I have not observed a failure of this kind for any other server. I don't really know what could be the issue or how to diagnose this further. If it helps, in this case (have not checked when this occurred previously): "wrong" address 162.242.239.16 "correct" 104.25.122.13 Lennart

2 1

Warning suppression pragmas
by Эдгар Жаворонков 27 Oct '15

27 Oct '15

Hi everyone! Do you know, if there is pragma for warning suppression? I want to implement something like warning suppression related to this ticket in GHC's Trac (https://ghc.haskell.org/trac/ghc/ticket/602) Or i need to implement that kind of pragma by myself? Thanks in advance! Edgar

6 16

unboundKey and fromIntegerClassOpKey unique overlap?
by Ben Gamari 27 Oct '15

27 Oct '15

Hello everyone, I noticed while looking through PrelNames that unboundKey and fromIntegerClassOpKey appear to share a unique in the master branch. Is this safe/expected? Cheers, - Ben

2 1