#11715: Constraint vs * -------------------------------------+------------------------------------- Reporter: bgamari | Owner: goldfire Type: bug | Status: new Priority: highest | Milestone: 8.4.1 Component: Compiler (Type | Version: 8.0.1-rc1 checker) | Keywords: Typeable, Resolution: | LevityPolymorphism, Roles Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): Just to record that Richard and I agreed that `constrainKind` currently has a bug. If `co :: Constraint ~ TYPE r`, then {{{ coercionKind (mkNthCo 0 (mkKindCo co)) }}} should succeed with `LiftedRep ~ r` but will fail because `Constraint` is syntactically `TYPE LiftedRep`. Stop-gap solution: * Make `coreView` do what `coreViewOneStarKind` does now; that is, expand `Constraint` to `TYPE LifteRep`. * Make the typechecker variants of `tcSplitTyConApp`, `tcSplitApp` use `tcView`; and make `tcView` '''not''' do this expansion. That is a more honest reflection of what is actually happening, until we fix it properly. Richard will have a go at this. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11715#comment:67 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler