#9692: Template Haskell reification for Data Families is buggy? -------------------------------------+------------------------------------- Reporter: hpacheco | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.3 Resolution: | Keywords: TemplateHaskell Operating System: MacOS X | Architecture: Unknown/Multiple Type of failure: | Difficulty: Unknown None/Unknown | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Description changed by hpacheco: Old description:

I have found an example where I think that the TH reification for data/newtype families is incorrect, in that if forgets non-instantiated type variables in instance declarations.

For the attached example, it will infer the Info:

{{{#!hs FamilyI (FamilyD DataFam TyFamReifyDefs.F [PlainTV a_1627399879,PlainTV b_1627399880] (Just StarT)) [DataInstD [] TyFamReifyDefs.F [ConT GHC.Types.Int] [NormalC TyFamReifyDefs.FInt [(NotStrict,VarT x_1627399881)]] []] }}}

Note how the variable x is not declared in the body of the DataInstD. Since it does not need to have the same name as the family-declared variable, substituing is non-trivial this way...

New description: I have found an example where I think that the TH reification for data/newtype families is incorrect, in that if forgets non-bound type variables in instance declarations. For the attached example, it will infer the Info: {{{#!hs FamilyI (FamilyD DataFam TyFamReifyDefs.F [PlainTV a_1627399879,PlainTV b_1627399880] (Just StarT)) [DataInstD [] TyFamReifyDefs.F [ConT GHC.Types.Int] [NormalC TyFamReifyDefs.FInt [(NotStrict,VarT x_1627399881)]] []] }}} Note how the variable x is not declared in the body of the DataInstD. Since it does not need to have the same name as the family-declared variable, substituting is non-trivial this way... -- -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9692#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#9692: Template Haskell reification for Data Families is buggy? -------------------------------------+------------------------------------- Reporter: hpacheco | Owner: goldfire Type: bug | Status: new Priority: normal | Milestone: Component: Template | Version: 7.8.3 Haskell | Keywords: TemplateHaskell Resolution: | Architecture: Unknown/Multiple Operating System: MacOS X | Difficulty: Easy (less than 1 Type of failure: | hour) None/Unknown | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Changes (by goldfire): * owner: => goldfire Comment: This gets a bit worse: reifying data families also includes kind parameters. Should be easy enough to fix, though... -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9692#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#9692: Template Haskell reification for Data Families is buggy? -------------------------------------+------------------------------------- Reporter: hpacheco | Owner: goldfire Type: bug | Status: new Priority: normal | Milestone: Component: Template | Version: 7.8.3 Haskell | Keywords: TemplateHaskell Resolution: | Architecture: Unknown/Multiple Operating System: MacOS X | Difficulty: Easy (less than 1 Type of failure: | hour) None/Unknown | Blocked By: Test Case: | Related Tickets: Blocking: | Differential Revisions: Phab:D355 | -------------------------------------+------------------------------------- Comment (by Richard Eisenberg ): In [changeset:"e319d6d2704edc2696f47409f85f4d4ce58a6cc4/ghc"]: {{{ #!CommitTicketReference repository="ghc" revision="e319d6d2704edc2696f47409f85f4d4ce58a6cc4" Reify data family instances correctly. Summary: Fix #9692. The reifier didn't account for the possibility that data/newtype instances are sometimes eta-reduced. It now eta-expands as necessary. Test Plan: th/T9692 Reviewers: simonpj, austin Subscribers: thomie, carter, ezyang, simonmar Differential Revision: https://phabricator.haskell.org/D355 }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9692#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#9692: Template Haskell reification for Data Families is buggy? -------------------------------------+------------------------------------- Reporter: hpacheco | Owner: goldfire Type: bug | Status: closed Priority: normal | Milestone: Component: Template | Version: 7.8.3 Haskell | Keywords: TemplateHaskell Resolution: fixed | Architecture: Unknown/Multiple Operating System: MacOS X | Difficulty: Easy (less than 1 Type of failure: | hour) None/Unknown | Blocked By: Test Case: th/T9692 | Related Tickets: Blocking: | Differential Revisions: Phab:D355 | -------------------------------------+------------------------------------- Changes (by goldfire): * status: new => closed * testcase: => th/T9692 * resolution: => fixed -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9692#comment:7 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler