#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 simonpj): That seems plausible. But reading the transitive closure of all interface files could be thousands of files! And 90% of the time when reifying a family or class you don't actually want an exhaustive list of all possible instances in all possible modules. A possible alternative is this: remove `[InstanceDec]` from `ClassI` and `FamilyI`. Instead you have to use `qReifyInstances` to find out about instances. Because the latter has a `[Type]` you can use that to know which interface files to load. To me that sounds simpler (delete code rather than add it), without really removing useful functionality. Simon -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8426#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler