#8426: one-shot compilation + TH doesn't see instances that is seen in batch mode ----------------------------+---------------------------------------------- Reporter: errge | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: | Version: 7.7 Template Haskell | Keywords: Resolution: | Architecture: Unknown/Multiple Operating System: | Difficulty: Moderate (less than a day) Unknown/Multiple | Blocked By: Type of failure: Other | Related Tickets: #7867 Test Case: | Blocking: | ----------------------------+---------------------------------------------- Comment (by errge): Yes, the exhaustive list can be big. I agree with your plan of just removing [InstanceDec] from ClassI and FamilyI, fixing the ambiguity. But actually I need the functionality of looking up instances without types. So what if we somehow expose that functionality directly? Meaning that only those users will pay the cost who explicitly want to do that. I see two options: - (clean) adding a new Q monad method for this, - (a bit hacky) specifying that qReifyInstances with an *empty* list parameter does that. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8426#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler