October 2018 - ghc-tickets

Re: [GHC] #2600: Bind type variables in RULES
by GHC 27 Oct '18

27 Oct '18

#2600: Bind type variables in RULES -------------------------------------+------------------------------------- Reporter: simonpj | Owner: simonpj Type: feature request | Status: closed Priority: lowest | Milestone: 8.8.1 Component: Compiler | Version: 6.8.3 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: | rename/should_compile/T2600 Blocked By: | Blocking: Related Tickets: #2110 | Differential Rev(s): Phab:D4894 Wiki Page: | -------------------------------------+------------------------------------- Comment (by mayac): It's worth mentioning that this has not been ''completely'' addressed. The following is now accepted: {{{ {-# RULES "myrule" forall t a. forall f x. from (tmap f (to x :: t a)) = map f (from (to x :: t a)) #-} }}} but, as per #10595, it does not behave as one would expect – the rules `"Class op tmap"` and `"Class op to"` may fire first. See that ticket for the appropriate workaround. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/2600#comment:27> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #13809: TH-reified data family instances have a paucity of kinds
by GHC 27 Oct '18

27 Oct '18

#13809: TH-reified data family instances have a paucity of kinds -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Template | Version: 8.0.1 Haskell | Keywords: TypeFamilies | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Consider this data family (and instances): {{{#!hs {-# LANGUAGE TypeFamilies #-} module Foo where data family Foo a data instance Foo ((f :: * -> *) (a :: *)) data instance Foo ((f :: (* -> *) -> *) (a :: (* -> *))) }}} These are two data family instances that GHC distinguishes by the kinds of their type parameters. However, Template Haskell does not give me the same insight that GHC has, because if I call `Language.Haskell.TH.reify ''Foo`, I get this: {{{#!hs FamilyI (DataFamilyD Foo.Foo [ KindedTV a_6989586621679025989 StarT ] (Just StarT)) [ DataInstD [] Foo.Foo [ AppT (VarT f_6989586621679026001) (VarT a_6989586621679026000) ] Nothing [] [] , DataInstD [] Foo.Foo [ AppT (VarT f_6989586621679026007) (VarT a_6989586621679026006) ] Nothing [] [] ] }}} Note that neither `f` nor `a` have a kind signature in either instance! This makes it completely impossible to tell which is which (aside from the order, which is brittle). It would make my life a lot easier if TH were to include kind signatures for each type variable in a data family instance. I can see two ways to accomplish this: 1. Include a `[TyVarBndr]` field in `DataInstD` and `NewtypeInstD` where each `TyVarBndr` is a `KindedTV`. 2. Walk over the `Type`s in a `DataInstD`/`NewtypeInstD` and ensure that every occurrence of a `VarT` is surrounded with `SigT` to indicate its kind. While (1) is arguably the cleaner solution, since it makes the kinds easy to discover, it is a breaking change. Therefore, I'm inclined to implement option (2) instead. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13809> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #2600: Bind type variables in RULES
by GHC 27 Oct '18

27 Oct '18

#2600: Bind type variables in RULES -------------------------------------+------------------------------------- Reporter: simonpj | Owner: simonpj Type: feature request | Status: closed Priority: lowest | Milestone: 8.8.1 Component: Compiler | Version: 6.8.3 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: | rename/should_compile/T2600 Blocked By: | Blocking: Related Tickets: #2110 | Differential Rev(s): Phab:D4894 Wiki Page: | -------------------------------------+------------------------------------- Changes (by RyanGlScott): * testcase: => rename/should_compile/T2600 * status: new => closed * resolution: => fixed * milestone: => 8.8.1 Comment: Thanks to mayac's hard work, we can now finally close this 10-year-old ticket. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/2600#comment:26> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #14268: Implement Explicit Foralls Proposal
by GHC 27 Oct '18

27 Oct '18

#14268: Implement Explicit Foralls Proposal -------------------------------------+------------------------------------- Reporter: johnleo | Owner: (none) Type: task | Status: new Priority: normal | Milestone: 8.4.1 Component: Compiler | Version: 8.2.1 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: -------------------------------------+------------------------------------- Implement Richard Eisenberg's Explicit Foralls proposal. https://github.com/ghc-proposals/ghc-proposals/pull/55 For details see the proposal: https://github.com/goldfirere/ghc-proposals/blob/instance- forall/proposals/0000-instance-foralls.rst -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14268> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #2600: Bind type variables in RULES
by GHC 27 Oct '18

27 Oct '18

#2600: Bind type variables in RULES -------------------------------------+------------------------------------- Reporter: simonpj | Owner: simonpj Type: feature request | Status: new Priority: lowest | Milestone: Component: Compiler | Version: 6.8.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #2110 | Differential Rev(s): Phab:D4894 Wiki Page: | -------------------------------------+------------------------------------- Comment (by Richard Eisenberg <rae@…>): In [changeset:"512eeb9bb9a81e915bfab25ca16bc87c62252064/ghc" 512eeb9/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="512eeb9bb9a81e915bfab25ca16bc87c62252064" More explicit foralls (GHC Proposal 0007) Allow the user to explicitly bind type/kind variables in type and data family instances (including associated instances), closed type family equations, and RULES pragmas. Follows the specification of GHC Proposal 0007, also fixes #2600. Advised by Richard Eisenberg. This modifies the Template Haskell AST -- old code may break! Other Changes: - convert HsRule to a record - make rnHsSigWcType more general - add repMaybe to DsMeta Includes submodule update for Haddock. Test Plan: validate Reviewers: goldfire, bgamari, alanz Subscribers: simonpj, RyanGlScott, goldfire, rwbarton, thomie, mpickering, carter GHC Trac Issues: #2600, #14268 Differential Revision: https://phabricator.haskell.org/D4894 }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/2600#comment:25> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15351: QuantifiedConstraints ignore FunctionalDependencies
by GHC 27 Oct '18

27 Oct '18

#15351: QuantifiedConstraints ignore FunctionalDependencies -------------------------------------+------------------------------------- Reporter: aaronvargo | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.5 (Type checker) | Keywords: | Operating System: Unknown/Multiple QuantifiedConstraints | Architecture: | Type of failure: GHC rejects Unknown/Multiple | valid program Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- The following code fails to compile: {{{#!hs {-# LANGUAGE QuantifiedConstraints #-} {-# LANGUAGE FunctionalDependencies #-} class C a b | a -> b where foo :: a -> b bar :: (forall a. C (f a) Int) => f a -> String bar = show . foo }}} {{{ • Could not deduce (Show a0) arising from a use of ‘show’ ... The type variable ‘a0’ is ambiguous }}} Yet it ought to work, since this is perfectly fine with top-level instances: {{{#!hs instance C [a] Int where ... baz :: [a] -> String baz = show . foo }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15351> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #15786: Hi Haddock: Enable haddock to generate docs from .hi-files
by GHC 27 Oct '18

27 Oct '18

#15786: Hi Haddock: Enable haddock to generate docs from .hi-files -------------------------------------+------------------------------------- Reporter: sjakobi | Owner: (none) Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 8.6.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): Phab:D5067 | Wiki Page: -------------------------------------+------------------------------------- -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15786> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #11238: Redesign the dynamic linking on ELF systems
by GHC 26 Oct '18

26 Oct '18

#11238: Redesign the dynamic linking on ELF systems -------------------------------------+------------------------------------- Reporter: trommler | Owner: trommler Type: task | Status: new Priority: normal | Milestone: 8.2.1 Component: Runtime | Version: 7.10.3 System (Linker) | Keywords: | Operating System: Linux Architecture: | Type of failure: Other Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- This ticket is to follow up on my comment on #11042. Let's give dynamic linking on ELF systems a second chance. I propose the following steps: 1. Collect required features 1. Write up and discuss and agree on a specification 1. Create regression tests for all features 1. Design and implement a new dynamic linker for GHCi 1. (optional) Make it work on Mac OS X too -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11238> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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[GHC] #10353: Haddock for Data.List should list instances
by GHC 26 Oct '18

26 Oct '18

#10353: Haddock for Data.List should list instances -------------------------------------+------------------------------------- Reporter: goldfire | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: | Version: 7.10.1 Documentation | Operating System: Unknown/Multiple Keywords: | Type of failure: None/Unknown Architecture: | Blocked By: Unknown/Multiple | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- I'd like to know the set of classes for which there are instances for `[]`. So, I naturally looked in the documentation for `Data.List`. However, because `Data.List` doesn't export `[]`, this list isn't there. Can this be fixed? (It's an honest question -- because of `[]`'s special syntax, I could see this fix being non-trivial.) -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10353> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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Re: [GHC] #4861: Documentation for base does not include special items
by GHC 26 Oct '18

26 Oct '18

#4861: Documentation for base does not include special items -------------------------------------+------------------------------------- Reporter: NeilMitchell | Owner: (none) Type: bug | Status: closed Priority: low | Milestone: 8.8.1 Component: Core Libraries | Version: 7.0.1 Resolution: fixed | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Documentation | Unknown/Multiple bug | Test Case: Blocked By: | Blocking: Related Tickets: #10353 | Differential Rev(s): Phab:D5167 Wiki Page: | -------------------------------------+------------------------------------- Changes (by harpocrates): * related: => #10353 -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4861#comment:16> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler

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