#11523: Infinite Loop when mixing UndecidableSuperClasses and the class/instance constraint synonym trick. -------------------------------------+------------------------------------- Reporter: ekmett | Owner: Type: bug | Status: new Priority: high | Milestone: 8.2.1 Component: Compiler (Type | Version: 8.0.1-rc1 checker) | Keywords: Resolution: | UndecidableSuperClasses Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: GHC rejects | Test Case: valid program | polykinds/T11523 Blocked By: | Blocking: Related Tickets: #11480 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj):
I've yet to figure out why the shorter example passes, but the longer, which doesn't seem to change the part that spins forever fails.
I explain precisely this in comment:14 above. You (implicitly) claim that there is a finite number of superclasses. I claim the contrary. We can't both be right :-). Maybe there's a bug in the example `Categories.h`? That's my current belief. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11523#comment:23 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler