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Re: [GHC] #2439: Missed optimisation with dictionaries and loops
by GHC 13 May '16

13 May '16

#2439: Missed optimisation with dictionaries and loops -------------------------------------+------------------------------------- Reporter: rl | Owner: simonpj Type: bug | Status: new Priority: lowest | Milestone: Component: Compiler | Version: 6.9 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Runtime | Unknown/Multiple performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by dfeuer): Replying to [comment:26 simonpj]: > I can't say I understand what is going on here, but in reify/reflect it seems that you want something akin to a local instance declaration. You want to write: > {{{ > reify (x :: a) (\ (p :: Proxy s) -> > ...In here we have (Reifies s a)... > ) > }}} > And you want to supply the local instance of `(Reifies s a)` yourself. > > Isn't this just what implicit parameters are for? They give you local instance declarations, in effect. The `reflection` package was largely motivated by [http://okmij.org/ftp/Haskell/tr-15-04.pdf Functional Pearl: Implicit Configurations -- or, Type Classes Reflect the Values of Types], by Oleg Kiselyov and Chung-chieh Shan, although their implementation is entirely different. Section 6.2 of the paper explains in depth why implicit parameters are insufficient. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/2439#comment:29> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4012: Compilation results are not deterministic
by GHC 13 May '16

13 May '16

#4012: Compilation results are not deterministic -------------------------------------+------------------------------------- Reporter: kili | Owner: niteria Type: bug | Status: new Priority: high | Milestone: 8.2.1 Component: Compiler | Version: 6.12.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Other | Test Case: Blocked By: 11362 | Blocking: Related Tickets: #10424 | Differential Rev(s): Phab:D910, | Phab:D1073, Phab:D1133, Phab:D1192, | Phab:D1268, Phab:D1360, Phab:D1373, Wiki Page: | Phab:D1396, Phab:D1457, Phab:D1468, DeterministicBuilds | Phab:D1487, Phab:D1504, Phab:D1508 -------------------------------------+------------------------------------- Comment (by Bartosz Nitka <niteria@…>): In [changeset:"5416fadb7387cbe89752faa875b2dade60655cf2/ghc" 5416fadb/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="5416fadb7387cbe89752faa875b2dade60655cf2" Refactor some ppr functions to use pprUFM Nondeterminism doesn't matter in these places and pprUFM makes it obvious. I've flipped the order of arguments for convenience. Test Plan: ./validate Reviewers: simonmar, bgamari, austin, simonpj Reviewed By: simonpj Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D2205 GHC Trac Issues: #4012 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4012#comment:168> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11768: Need a way to attach Haddock documentation to derived instances
by GHC 12 May '16

12 May '16

#11768: Need a way to attach Haddock documentation to derived instances -------------------------------------+------------------------------------- Reporter: bgamari | Owner: Type: feature | Status: new request | Priority: normal | Milestone: 8.2.1 Component: Compiler | Version: 7.10.3 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- In the case of `base` we'd like to be able to attach Haddock `@since` annotations on new typeclass instances. Unfortunately many instances are derived, which we can't currently attach Haddock documentation to. Fix this. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11768> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4012: Compilation results are not deterministic
by GHC 12 May '16

12 May '16

#4012: Compilation results are not deterministic -------------------------------------+------------------------------------- Reporter: kili | Owner: niteria Type: bug | Status: new Priority: high | Milestone: 8.2.1 Component: Compiler | Version: 6.12.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Other | Test Case: Blocked By: 11362 | Blocking: Related Tickets: #10424 | Differential Rev(s): Phab:D910, | Phab:D1073, Phab:D1133, Phab:D1192, | Phab:D1268, Phab:D1360, Phab:D1373, Wiki Page: | Phab:D1396, Phab:D1457, Phab:D1468, DeterministicBuilds | Phab:D1487, Phab:D1504, Phab:D1508 -------------------------------------+------------------------------------- Comment (by Bartosz Nitka <niteria@…>): In [changeset:"6bf0eef74d2b2ce9a48c7acc08ca2a1c0c8a7fbc/ghc" 6bf0eef/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="6bf0eef74d2b2ce9a48c7acc08ca2a1c0c8a7fbc" Kill varEnvElts in specImports We need the order of specialized binds and rules to be deterministic, so we use a deterministic set here. Test Plan: ./validate Reviewers: simonmar, bgamari, austin, simonpj Reviewed By: simonpj Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D2197 GHC Trac Issues: #4012 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4012#comment:167> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4012: Compilation results are not deterministic
by GHC 12 May '16

12 May '16

#4012: Compilation results are not deterministic -------------------------------------+------------------------------------- Reporter: kili | Owner: niteria Type: bug | Status: new Priority: high | Milestone: 8.2.1 Component: Compiler | Version: 6.12.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Other | Test Case: Blocked By: 11362 | Blocking: Related Tickets: #10424 | Differential Rev(s): Phab:D910, | Phab:D1073, Phab:D1133, Phab:D1192, | Phab:D1268, Phab:D1360, Phab:D1373, Wiki Page: | Phab:D1396, Phab:D1457, Phab:D1468, DeterministicBuilds | Phab:D1487, Phab:D1504, Phab:D1508 -------------------------------------+------------------------------------- Comment (by Bartosz Nitka <niteria@…>): In [changeset:"01bc10965d993babf6c2c35d340655f683ba0ca2/ghc" 01bc1096/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="01bc10965d993babf6c2c35d340655f683ba0ca2" Document zonkTyCoVarsAndFV determinism I've changed it to use nonDetEltsUFM and documented why it's OK. Test Plan: it builds Reviewers: bgamari, austin, simonmar, goldfire, simonpj Reviewed By: simonpj Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D2204 GHC Trac Issues: #4012 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4012#comment:166> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4012: Compilation results are not deterministic
by GHC 12 May '16

12 May '16

#4012: Compilation results are not deterministic -------------------------------------+------------------------------------- Reporter: kili | Owner: niteria Type: bug | Status: new Priority: high | Milestone: 8.2.1 Component: Compiler | Version: 6.12.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Other | Test Case: Blocked By: 11362 | Blocking: Related Tickets: #10424 | Differential Rev(s): Phab:D910, | Phab:D1073, Phab:D1133, Phab:D1192, | Phab:D1268, Phab:D1360, Phab:D1373, Wiki Page: | Phab:D1396, Phab:D1457, Phab:D1468, DeterministicBuilds | Phab:D1487, Phab:D1504, Phab:D1508 -------------------------------------+------------------------------------- Comment (by Bartosz Nitka <niteria@…>): In [changeset:"925b0aea8edc1761fcc16feba1601bea38422c92/ghc" 925b0aea/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="925b0aea8edc1761fcc16feba1601bea38422c92" Make absentError not depend on uniques As explained in the comment it will cause changes in inlining if we don't suppress them. Test Plan: ./validate Reviewers: bgamari, austin, simonpj, goldfire, simonmar Reviewed By: simonmar Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D2203 GHC Trac Issues: #4012 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4012#comment:165> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12049: `OverloadedStrings` for types
by GHC 12 May '16

12 May '16

#12049: `OverloadedStrings` for types -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 7.10.3 Keywords: | Operating System: Unknown/Multiple CustomTypeErrors | Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Is there any sense in adding {{{#!hs class IsSymbol a where type FromSymbol (str :: Symbol) :: a instance IsSymbol ErrorMessage where type FromSymbol str = GHC.TypeLits.Text str instance IsSymbol ErrorMessage where type FromSymbol str = str }}} where `FromSymbol` gets placed before type-level string literals: {{{#!hs TypeError ("Warning: ":<>:ShowType ty:<>:" is odd.") }}} analogous to `Data.String.IsString`. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12049> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11099: Incorrect warning about redundant constraints
by GHC 12 May '16

12 May '16

#11099: Incorrect warning about redundant constraints -------------------------------------+------------------------------------- Reporter: diatchki | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.11 (Type checker) | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- The following program results in an incorrect warning about a redundant constraint: {{{ {-# LANGUAGE TypeFamilies #-} type family SomeFun a f :: (SomeFun i ~ [a], Read a) => proxy i -> a f _ = read "HELLO" }}} This is the warning: {{{ Redundant constraint: SomeFun i ~ [a] In the type signature for: f :: (SomeFun i ~ [a], Read a) => proxy i -> a }}} I tried it on GHC version 7.11.20151029 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11099> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #12046: AllowAmbiguousTypes doesn't work with UndecidableSuperClasses
by GHC 12 May '16

12 May '16

#12046: AllowAmbiguousTypes doesn't work with UndecidableSuperClasses -------------------------------------+------------------------------------- Reporter: MikeIzbicki | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1-rc3 (Type checker) | Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Given the code below, `test1` and `test2` are the same except the former has an ambiguous type and the latter does not. The compiler rejects the former and accepts the latter. {{{ {-# LANGUAGE UndecidableSuperClasses #-} {-# LANGUAGE AllowAmbiguousTypes #-} {-# LANGUAGE TypeFamilies #-} class A (T a) => A a where type T a test1 :: forall a. A a => () test1 = () test2 :: A a => proxy a -> () test2 _ = () }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12046> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4239: -ddump-minimal-imports vs. type operators
by GHC 12 May '16

12 May '16

#4239: -ddump-minimal-imports vs. type operators -------------------------------------+------------------------------------- Reporter: nomeata | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.3 Resolution: | Keywords: newcomer Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: T4239 Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by mpickering): * keywords: => newcomer -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4239#comment:7> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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