#15793: Type family doesn't reduce with visible kind application -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.1 Resolution: | Keywords: | TypeApplications Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by simonpj): * status: closed => new * resolution: invalid => Comment: But surely we should reject {{{ F2 @a = Maybe a }}} on the grounds that, well, `F2` has arity 0, so you can't supply an `@ty` arg on the left?

We don't yet have the syntax to declare a type family whose argument is both invisible and non-dependent.

Is another way to say this that the final argument of a type family must be `Required`; it cannot be `Specified`? What about `Inferred`? I think that is possible, isn't it? We should document this somehow in the user manual. Re-opening for these reasons. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15793#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#15793: Type family doesn't reduce with visible kind application -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.1 Resolution: | Keywords: | TypeApplications Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: #15740 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by goldfire): I think this is likely #15740, but you're right that I was too hasty in closing this. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15793#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#15793: Type family doesn't reduce with visible kind application -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: bug | Status: closed Priority: normal | Milestone: 8.8.1 Component: Compiler | Version: 8.6.1 Resolution: fixed | Keywords: | TypeApplications Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: | typecheck/should_compile/T15793 Blocked By: | Blocking: Related Tickets: #15740 | Differential Rev(s): Phab:D5229 Wiki Page: | -------------------------------------+------------------------------------- Comment (by Richard Eisenberg ): In [changeset:"17bd163566153babbf51adaff8397f948ae363ca/ghc" 17bd1635/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="17bd163566153babbf51adaff8397f948ae363ca" Visible kind application Summary: This patch implements visible kind application (GHC Proposal 15/#12045), as well as #15360 and #15362. It also refactors unnamed wildcard handling, and requires that type equations in type families in Template Haskell be written with full type on lhs. PartialTypeSignatures are on and warnings are off automatically with visible kind application, just like in term-level. There are a few remaining issues with this patch, as documented in ticket #16082. Includes a submodule update for Haddock. Test Plan: Tests T12045a/b/c/TH1/TH2, T15362, T15592a Reviewers: simonpj, goldfire, bgamari, alanz, RyanGlScott, Iceland_jack Subscribers: ningning, Iceland_jack, RyanGlScott, int-index, rwbarton, mpickering, carter GHC Trac Issues: `#12045`, `#15362`, `#15592`, `#15788`, `#15793`, `#15795`, `#15797`, `#15799`, `#15801`, `#15807`, `#15816` Differential Revision: https://phabricator.haskell.org/D5229 }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15793#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler