Hello glasgow-haskell-users, i've rather complicated class structure: class BufferData a where instance (FastBufferData a) => BufferData a where class FastBufferData a where instance (Storable a) => FastBufferData a where of course, it's compiled with -fallow-undecidable-instances -fallow-overlapping-instances -fallow-incoherent-instances BufferData class includes procedure `write`: class BufferData a where write :: OutStream -> a -> IO () there is writeAll procedure which uses this `write` and therefore should be able to write any BufferData instance: writeAll receiveBuf sendBuf cleanup x = bracket (create receiveBuf sendBuf cleanup) (closeOut) (\buf -> write buf x) it works great in 6.6.1 but in 6.8.2 GHC infers that writeAll can write only Storable instances, so i was forced to add signature to writeAll: writeAll :: (BufferData a) => RecvBuf -> SendBuf -> Cleanup -> a -> IO () the same problems raised many times when i switched from 6.6.1 to 6.8.2 - lots of procedures need to add signatures because by default 6.8.2 decided that they are restricted to Storable does GHC developers interested in minimal test case for this problem? -- Best regards, Bulat mailto:Bulat.Ziganshin@gmail.com